person A: I have a friend who's been weight lifting with me for years now and he looks better than me. I wish I had his genetics!
person B: Oh_comma_ I totally understand.  It's frustrating when you feel like you're putting in the same effort (or more!) and it works better for other people.  
person A: It sure is frustrating_comma_ but I can't say I haven't made great progress myself. But his progress is insane!
person B: Well_comma_ it's good that at least you're making progress!  It would be crazy frustrating if you weren't.  Congrats on your hard work paying off. 