When someone says go for it, it means to put forth necessary effort or energy to do or pursue something.
Used as words of encouragement especially in the face of doubt.
To do what you need without additional thought.
1. If you want the girl, stop worrying and just go for it.
2. We need to build a team strategy on this project and go for it.
3. If you feel like you want to attend arts school instead of pursuing your parents’ dream of becoming a lawyer, I say go for it!
4. A: I really want a donut but I’m scared that I’ll put on weight if I have one.
B: Just go for it!
accomplish, achieve, begin, carry out, do, execute, exert oneself, get in there, go all out, pull out all the stops, put one’s heart and soul into it, take a risk, use every muscle