For me, I worship/pray to God because I appreciate all the things he has done to be. I.. I just do it you know. I think worshipping him is one way to express my gratitude to him. I worship at my own will.
Personally, I dont think it is REQUIRED to do so. But by just believing in God, not doing anything about it and just keep it at the back of your mind is kind of... not morally right.
Yay!!!