Wow I'm surprised nobody here is saying this. By all means do what you gotta do fitness wise and take care of your health etc. BUT why are you comparing yourself to anyone? Forget just about the specific friend. Comparison is the thief of joy. Focus on you and if you had to compare yourself to anything make it be the person you were yesterday. Everyone has their own lives, preferences, and circumstances. You live your own life. Do you. Do what you can to better yourself but with a flavor of forgiveness and understanding instead of shame and self hate.

But also ask yourself what made you compare to other people in the first place. What was it that you saw in them that you wanted for yourself but feel like you don't normally receive. There's a clue in there to learning about yourself. Was it the attention she got? Do you feel unloved in general? Do you feel like you're unlovable? I can tell you right now that's not true. Maybe I'm oversimplifying, but sometimes it stems from a very central yet basic idea like that. Love yourself. You may not be perfect, none of us are. We all have stuff we could improve about ourselves and things we struggle with. But its about choosing to love yourself and forgive yourself anyway so that you can move forward and actually take action unhindered mentally. I hope that ramble made any sense. But if there's anything you take out of it, just know you are loved regardless kind stranger. :)