I wish I could delete the moments where I ever felt "old" because to think that now is just stupid. I saw the number 24 written on the cover of a book while on the train, and clearly thought these three things -- I am older than that number. I have not read that book. There is so much I have yet to do.
Never settle. There is always more for you to learn. As you get older, this means that you have to be vulnerable. This means putting yourself in new and different situations, and not being the expert. It means creating a time and space to step out of your boundaries and try to understand someone else's perspective.
Diets don't address many of the root issues of weight gain: emotions, habits and unconscious behavior. In fact, they promise that when you diet, you'll become the perfect person. But, spoiler alert, even at a smaller size, you're still the same person. Do the more challenging emotional work and the results will pay off for good.