How can I become water?

It means that you should be flexible.

For example, if you were sparring against a boxer, instead of punching and resisting, just kick. If you were sparring against somebody who took a kicking-based martial art, punch. If you are facing a kick-boxer, grapple. If you're facing a wrestler, strike. If you're facing a powerhouse with no stamina, try to make the fight last long. If you're facing a weak guy with good stamina, try to make the fight end as early as possible. If you're facing a big slow guy, use the slowness as an advantage. If you're facing a small fast guy, use the smallness as an advantage.

The idea is that there's no 1 way (only kicking, only punching) to deal with all the multiple situations you'll deal with. You have to adjust to your surroundings accordingly. The more adaptable to change you are, the more ability you'll have to survive.

Remember that most of our body IS water. We also have many joints so that each can move as we practice, in sequence. This allows the body to flow.

It is the habits of tension and the mental habit of acting/stopping that turns us into cement. You first learn to perceive and act at the same time, rather than come in with a blind flurry of techniques and then stop and look to see what happened. Each muscle and joint of the body must be able to respond and change from second to second according to what is actually going on.

In Tai-chi-Chuan you learn to divide each second into many responses and you divide your body into each muscle and joint. Each body part develops its own awareness and so can respond directly without getting direction from the thinking mind. This allows the body to be efficient and relaxed.

You learn to respond with the least amount of movement and tension possible so you stay centered, calm and relaxed even during fighting. Yet the intricacy of movement allows you to evade the strikes easily. You never place your attention at the focal point of his power (by blocking) but just move into his open areas AS he strikes. This requires that you become aware of what is going on in his body and mind to respond at the same time he acts. And this allows you to stay relaxed, like water.

Becoming like water is a very technical training, which is the basis of Tai-chi-Chuan training, but can also be found in other martial arts.

I'm pretty sure he's referring to this:

"Don't get set into one form, adapt it and build your own, and let it grow, be like water. Empty your mind, be formless, shapeless — like water. Now you put water in a cup, it becomes the cup; You put water into a bottle it becomes the bottle; You put it in a teapot it becomes the teapot. Now water can flow or it can crash. Be water, my friend."

- Bruce Lee

It's basically an emphasis on adapting to your opponent and relaxing rather than resisting the pace he/she sets, you react upon it. Instead of trying to force your way, you let them dictate, and you give a response.

Don't take it too literally. To be like "water" just means to be flexible. To loosen up your body and to just flow. Follow through. But become physically and mentally flexible as well. Don't be closed to your options but also be able to leave your body loose and relaxed enough to allow those options to happen.

Ahhh this is a Bruce Lee thing, you must flow like water and be fierce like water. Look up his saying and youll know

Crow fly to great super bronze monkey. Monkey pour spirit into serpent. Serpent transform being into water niad.

You're 65% water. Your argument is invalid.