Coaching Basics

There are only 3 reasons a person doesn't do what you're telling them to do.
A - You didn't tell them
B - They can't
C - They won't

So if you tell them, it only leaves the other 2.
B - is your fault for asking someone to do something they aren't capable of.
C - is also your fault for playing someone who won't do what you're asking them to do.

Change the what you're asking them to do, change the way you're asking them to do it and get rid of those who won't.

"I don't care what kind of athlete you are, I don't care what grade you are in, if you want to play defense for me you will come to weights and I will only play people who are football players."