Everyday when I finish work, I feel even more energise than before I started. That's a good sign. Your work energise you.
Sometimes when you go and catch up a friend, you feel happy and energise after that.
There are times you feel exhausted and drained and noticed you don't feel good after that. Their energy drain you.
These days I am always consciously aware what and who energise me, and what or who drain me. And I am also very aware that I would definitely not drain others.