I agree with you friend that you are happy in the things in which you want to be happy it means that you always feel happiness and peace in those things in which you really have any interest as you have also told us through example.

I agree that if a student is really chosing a career and he choose another career of his interest due to the family pressure then he will not find happiness in it and due to unhappy behaviour we cannot perform very well.

Conclusion is That we should take care of our interest and our happiness so that in future we may don't find any difficulty