I think exercising is a big one. I know plenty of overweight JW's with really low self esteems but they just don't feel they have time to exercise with all the studying and reading and meditating and praying they have to do, plus the end is so close anyway.
I was one of them, so I know this is true.
And I think not having a college education is helpful to WTS in several ways: you are so overworked and underpaid you don't have time to think for yourself and realize the religion you belong to is a bogus cult AND you are are not educated to think for yourself so you don't even know you are not thinking for yourself.
Does that make sense?