Not long ago it was spring and now it is becoming summer. From spreading roots, shoots and stems have appeared and now countless buds burst forth and blossom and then fall to the ground. In the monastery garden, the ferns have unfolded and now tower above spreading moss. Skunks and squirrels and hundreds of finches have come to drink from the stream along with a mother racoon and her young who also stopped by the front porch to investigate the Buddha rupa and offering bowl. And the Engleman ivy creeps up the building with small fingers that attach themselves to the brickwork.
Not long ago, it was night and now its morning. Not long ago, we began this Dharma Assembly and not too long from now, it will already be over. Not too long from now, someone will be listening to the recording of this Dharma Talk and I will have been dead for years. It all happens so quickly. This happening, this activity, this exertion of the reality of impermanence is all that is ever going on. Our practice is the practice of opening to this reality and realizing it as part of our own natures.
Virya, or exertion, is one of the six Paramitas. The Paramitas describe aspects of being Awake to Reality that unfold through the process of practice. You have to start off with some initial element of, say, generosity, exertion, and so forth, but they unfold dynamically as you actually practice. In the Mahayana schema there are six Paramitas:
Dana Paramita: generosity
Sila Paramita: Integrity or discipline
Ksanti Paramita: Patience or flexibility
Virya Paramita: Exertion
Dhyana Paramita: Zazen or practice
Prajna Paramita: Radical insight or perfectly knowing emptiness
Of these six, exertion is the most important Paramita because without exertion, nothing is going to happen. We will just sit around instead of actually sitting and doing the practice of realization.
There are many ways of understanding what virya is, such as "the sustained effort to overcome laziness"; vitality; enthusiasm; prowess and potency. But none of these understandings are adequate to what we need to understand through and within our practice.
In the book, "The Pathless Path", Zen Master Anzan Hoshin says about virya:

…Exertion may well be the most crucial of the Paramitas that we must develop. Without it, our practice can only be based on images and ideas, expectations and concepts. Exertion is like the fine steel of a sword blade. Without a strong blade, it does not matter how sharp or well-honed the edge is, because the blade will snap off at the handle as soon as it is drawn. In fact, without exertion, the blade will just stay in the scabbard.
To truly sever the confusion and duality of the usual mind with Manjusri's sword of Dhyana and Prajna we must be able to exert THIS fully, holding nothing back. If we do not sever the duality and strategies of the usual mind, then the seamless unity of the whole moment will never be lived.

In order to practice beyond strategy we must first see our strategies, not to follow them but to open beyond them. And so it is of utmost importance to stay with the instructions we have been given and refrain from making up and following our own version of the practice. Not propagating means not propagating any thoughts, feelings, theories and concepts about anything and this of course applies to our practice as much as it does any other topic that might come up while one is sitting. Thinking about practicing is not practicing. If you have not been specifically told to do something in your practice, then don't do it. Ask about it if something has caught your attention and you think it worth discussing, but don't experiment.
There are ten thousand strategies that we may attempt to apply to our practice, but in the end they all fall apart. For instance, hunkering down around the breath instead of using the breath as a touchstone from which to open to the whole of experiencing will just lead to more and more discursiveness. Students will also sometimes "watch" themselves practicing, as though following themselves around. If you follow yourself around, you will inevitably get in your own way. Continuously "assessing" one's "progress" is another pitfall that frequently comes up. Letting yourself passively drift into storylines and justifying this by occasionally checking to see if you are still breathing or if the wall is still there and then going straight back into the storyline is not exerting yourself in your practice. Over and over again I see students allowing themselves to fall into the same cesspools of confusion and torpor again and again. Don't just muck about in that stuff. Don't put your face in it. STAND UP from it. How do you do that? Sit up straight, Shut up. Practice.
The Roshi continues,

Exertion must be clean, it must be free of strategies and romantic notions about enlightenment and Buddhahood. There is no use gritting your teeth and locking your legs in full lotus and trying to pull yourself out of samsara and into nirvana.

There is simply nowhere else that you can be than right here, in this moment. Exertion does not imply some kind of spiritual gymnastics or punching out self-image.
Exertion is surrendering completely into attentiveness again and again. Exertion is being utterly straightforward with whatever arises. Exertion is doing whatever needs to be done, and doing so as completely as possible: taking a complete step, a complete breath, touching completely, hearing completely. This is complete and wholehearted practice.
Without this kind of exertion all of this would just be talk. We could say, "Oh yeah, everything is Buddha Nature inhering within itself. Don't struggle, just wake up." And we could go through the motions, sit on the zafu and stare at the wall for the prescribed number of minutes and bide our time. But what is time? Who is this?
Zen is "the direct transmission outside words and letters, pointing directly to the mind," pointing directly to the moment, directly to just this.
The wall exerts itself completely and directly as the wall. No doubts about it, nothing held back, nothing pushed forward. No matter whether you call it a wall or not, the wall exerts itself completely as what it is. This exertion is what the wall is.
Complete exertion is our practice, it is what practice is. Cutting through blame and fame, hope and fear, here we are. Breathing in, breathing out.
Without calling it samsara or nirvana, good or bad, self or other, let us exert ourselves completely in just this. If you are walking, walk; if you are talking, talk; if you are listening, listen. In complete exertion, in whole-hearted practice, the Buddha Dharma begins to exert itself. If we exert ourselves completely as this breath, then this breath will begin to exert itself. Seeing has its own intelligence, hearing has its own intelligence; you are redundant. All struggle drops away and we discover that we don't even have to try to know anything.
Everything is self-known without a knower, without a known. Limitless Knowingness begins to dawn and continues to blaze as the mandala in which enlightenment is continuously born.
This occurs nowhere else and in no other time than just this. So let us exert ourselves completely, practice completely, realize the Way completely.
Moment after moment, the world opened by practice extends in the Ten Directions, exerting itself as sun and rain and wind. It exerts itself as the pain in your knee and the pleasure of cool water on your face on a hot summer day. It exerts itself as the creaking of the floorboards on which you walk in kinhin. It exerts itself as the empty toilet roll that needs changing, the printer that won't print, the bill that can't be paid, and exerts itself as your job, your family and your friends. It exerts itself right now and in each moment as everything you experience. The world presents itself as rich, playful, ever-changing details.
You are not separate from the exertion of the world and the possibility of your Waking Up exists only because of the possibility of your exertion. Unless you exert yourself, you're not really sitting, you are just sitting around. But if you're pushing and pulling you're not sitting either. You are doing some weird meditation trip.
When we are really practicing, we are not making anything happen. We do not make the sensations happen or the colours and forms and sounds happen. They are already present. All that we need to do is let attention fall open to what is already the case. Sensations and colours and forms and sounds already exert themselves. When you release yourself into this exertion, you release yourself into that which exerts itself as you and exerts itself as the world.
In the teisho series, "Wild Time: Commentaries on Dogen zenji's "Uji: Being Time", the Roshi says,

Everything arises here and now.
It is not that this arising is a matter of here plus now.
Here is now.
Now is here.
It is not a matter of time plus place equals our experience.
It is now equals here equals is.
This is the exertion that you must release yourself into in order to realize who you are.
Without the exertion of you releasing yourself, nothing is realized, nothing is real.
All that you have are stories,
descriptions,
presumptions,
and
fixations.
By releasing yourself into That which unfolds itself as everything,
which arises everywhere as everything, right now,
you realize this arising.
You are the realization of this arising.
Without the exertion that needs no one to do it,
that is done by no one at all
but is simply exertion exerting itself,
Nothing would arise.

We are open to the exertion of this moment only when we do not hold ourselves back or get in our own way by following tendencies and habits. Actually recognizing that a pattern is a pattern, that a tendency is a tendency, can be difficult. We have used patterns and tendencies to define ourselves and can sometimes find it impossible to believe that we can be any other way. But as Roshi says, "We are really only ourselves as we really are when we are open to reality as it is." And we can do this so easily. All that we need to do is actually sit when we sit. Just sitting around just won't do it. Just sitting back and hoping it will all work out won't do it.
Open to this breath. Now. Now. I mean it. Now. I really really mean it. Please? It's not just for your own good. There is no good that you can do without doing this. Look at this world. Read the newspapers. Or just actually listen to the nasty stuff you tell yourself about yourself. And about other people. It's terrible. The problem is that every body else is saying these terrible things to themselves about themselves and every one else. And they're out there: driving cars, shooting guns, buying shoes, having babies, ruling countries, writing code, playing music, cooking and eating and all of the things that affect every one and every thing else in the world. Someone has to do these things that doesn't have such a grudge about actually doing something clearly and completely and well. So, please, exert yourself. Exert yourself by just stopping. Stop that stuff. Just sit up straight. Now.
I mentioned before how quickly everything goes. Now this Dharma Talk is almost finished. Spring comes and goes, summer comes and goes, autumn comes and goes, winter comes and goes. You and I and all of us come and go. So let go. Let go INTO this coming and going. Exert yourself by not following yourself around and open to the ten directions all around you.
Now I've finished talking. You should stop talking to yourselves too. And so let's all sit.