I sometimes let people walk over me or do ridiculous favors because seeing others happy makes me happy.
Does this really make you feel happy?
I feel it makes me happy for the most part.
You are a people pleaser, I can see that in your personality as clear as day. There is such a thing as boundaries which you need to implement too, that way everyone is happier than you think. Without boundaries one day someone will end up trying to do bad to you or even murder you to get what they want.
What if I don't want to feel bad?
There are other ways to make yourself feel happy and others at the same time. You should find people in your life that appreciate the nice things that you do for them. Focusing on these people would be the best thing for your mental health.