This is a little controversial, but I think it’s okay to be unhappy with who you are. You shouldn’t be unhappy with everything about yourself; that’s unhealthy. But if you’re ready for a change, then you are looking to grow. And I can appreciate someone trying to better themselves.
Change is stressful
Why do humans get ulcers? It’s a bit of a dated topic at this point. Robert Sapolsky’s renown book “Why Zebras Don’t Get Ulcers” came out 25 years ago. The simple points of stress are pretty well understood, especially in health and fitness.