22, because while my mental health went to hell at 13, and I basically had endometriosis from my first period at age 9, I didn't develop any of my major physical disabilities/chronic pain conditions until I was 23. Also, I was in pretty good shape back then, apart from the endo...hmmm. I guess I'd want to be 22 forever, but only if I could have a complete hysterectomy like I did at age 28. I just couldn't handle having periods again after 4 years of freedom. Come to think of it, the 4-year anniversary of my hysterectomy was yesterday. Man, time flies.