It's been hard to lose weight!!!

I had my baby boy 4 months ago and I'm finding myself gaining more weight after my baby!! I need suggestions!! What did you guys try?? Ever felt too lazy? What did you do??? I did get the debo shot! And I was on it for 2 months, closely 3. I've heard that it make you gain more weight. So I'm thinking of not getting it anymore. But still. H.E.L.P! Please :( my knees are staring to hurt.