Go For It
Meaning/Usage: To encourage someone to do something that they have planned
Explanation: The literal meaning is to "decide on" or "choose." However, it is commonly used informally to encourage them to take action on something they are thinking about doing.
some examples to explain more.
1-I know you want that job. Go for it!
2-If you want to ask her out you're going to have to just go for it.
3-Don't let anyone stand in the way of your dreams. Go for it!
Conversation
A-I really like her. Should I ask her for her phone number?
B-Go for it man!" You have nothing to lose.
Other Common Sentences
Just do it.
Take action on it.
Be proactive.