In my own words and understanding, Zen is the art of being at peace with yourself, your surrounding and your soul (or the higher being in you).
Meditation is the art of freeing your mind to get to Zen. It is a spiritual practice that allows you to settle and remove the negativities that our physical bodies incur on a daily basis.
Yoga on the other hand is the freedom of one from the physical bounds. It makes you master your body in order to be prepared for mental exercise (meditation) and then allow you to move forward with spiritual practice (zen).
What about forgetfulness? Isn't the opposite of this also similar to saying you are letting go? How do you let go of something that has a very big effect on you? Like losses.. of loved ones, of happiness?
If you do Yoga + Meditation, and move forward with Zen, does that also mean saying you want to forget?