Don't Know How To Say No

I have a problem that I don’t know how to say no to people. It is just my personality I think but I really want to change it. Sometimes, it bothers me because no matter what how busy I am with my kids, I never say no if someone ask for my help. For example, they want me to come over in their house. Even it is hard for me to step out from the house, I still do and bring my children.

I wish it is easy to say no but when it comes to just like people I know, I can’t say no.