Welcome to 3FC!
Great advice from Sharon.
Yesterday I was thinking about what I did as a teen to make me one of those annoying slim people who could eat vast quantities of food without gaining an ounce.
I ran five times a week.
Walked everywhere instead of taking elevators, buses, etc.
Probably drank more liquids than I do now.
Held my stomach in all the time, which made for some wicked stomach muscles.
Probably ate a more balanced diet (despite all the snacking I did), as I was still living at home. Now, I have this immature idea (at 43!?) that I can eat whatever I want because I'm "all grown up". How dumb is THAT!?
You're at the perfect time of your life to learn all the "tricks", and to work them into a lifestyle that'll get you through difficult times.
Best wishes!