It took me until my 50s to stop being self-conscious about my slender body and skinny arms. Exercising more helped a bit but it was mostly in my head. My advice - love yourself now! (The sign was for a Twitter pro-nudity campaign)
40(f) - 130lbs (ish) - 5ft 7. my ass isn't as high and pert as it once was, neither are my breast and there's cellulite. But, it's my body, I've earned every mark and I love them all