English question

Yesterday, I found some sentences which i couldn't understand on SAT.
1. Athletes and actors share much.
2.They share the need to make gesture as fluid and economical as possible, to make out of a welter of choices the single, precisely right one.
3. They share the need for thousands of hours of practice in order to train the body to become the perfect, instinctive instrument to express.
4. Both athlete and actor, out of that abundance of emotion, choice, strategy, knowledge of the terrain, mood of spectators, condition of others in the ensemble. secret awareness of injury or weakness, and as nearly an absolute concentration as self, must be able to change the self so successfully that it changes us.

Through 1 to 4 is the first paragraph of a passage, and I understand 1 and 2.
Could you tell me what 3 means?
And why isn't there any verb in 4, i wonder the verb in 4 is "share" which follows "Both athlete and actor" right?

3. means that they both need to practice many hours so that their body becomes their tool to express themselves perfectly and instinctively.

4. The verb is "must be able to change."

I wonder if there is any other forum for asking English language related questions? :)

Thank you very much, AK.
Thanks to your English,i got it easily.

Yes,I found that this question shouldn't have been posted here after submitting.
Sorry for my imprudency.