Philosophical statement made when you put life in perspective, you acknowledge that you are truly blessed, you are truly lucky, and you have all but great things ahead of you.
Hypothetical: You are surrounded by all your friends, it's your birthday, you are having a great time, before you take a shot, you reminisce....
Being in your feels means that you have a strong emotional reaction (often that emotion being sadness/feeling empty) to something that happened of that has been said.
person 1: Damn that movie was so sad Person 2: Yeah, i see you’re in your feels. Me too