How to Get Children Over People Pleasing?

Hey all. I need some advice regarding my nephews (ages 12, 10, and 8).

I am very close to my nephews and see them almost everyday. Their mother is a manipulator and their father is a doormat. Two of the boys are people pleasers. They do anything their mother (and some other similar family members) wants without thinking of what they want, even when it’s clear they want something different. An example is sports. My oldest nephew loves baseball and for some reason their mother hates baseball. Their mother tells him that he should like lacrosse instead. Eventually, he is signed up for lacrosse and sad all season. This is just one example but it is with everything in all three boys’ lives.

Now I am not a people pleaser at all. To be honest, I just don’t get it. I just want the boys to be able to be capable of independent thought and express their true feelings.

So adult people pleasers, what would you have wanted someone to do to help you get over people pleasing tendencies when you were younger?