How much 'ego' do you need? Just enough so that you don't step in front of a bus.

So the most difficult thing is always to keep your beginner's mind. There is no need to have a deep understanding of Zen. Even though you read much Zen literature, you must read each sentence with a fresh mind. You should not say, "I know what Zen is," or "I have attained enlightenment." This is also the real secret of the arts: always be a beginner. Be very very careful about this point. If you start to practice zazen, you will begin to appreciate your beginner's mind. It is the secret of Zen practice.

It must be obvious...that there is a contradiction in wanting to be perfectly secure in a universe whose very nature is momentariness and fluidity.

From True Emptiness The Wondrous Being Appears

You can't make a date with enlightenment.

Time goes from present to past.

People say that practicing Zen is difficult, but there is a misunderstanding as to why. It is not difficult because it is hard to sit in the cross- legged position, or to attain enlightenment. It is difficult because it is hard to keep our mind pure and our practice pure in its fundamental sense.