Your muscles will start to develop on their own as you go through puberty to a certain extent. And physical activity will improve that. I don't lift weights but do a lot of swimming, so my shoulders have gotten a bit wider, my legs are bigger and my glutes are firmer. Abs have developed a bit too

I noticed becoming stronger much more than I noticed muscles becoming more bulky.

i have noticed that my legs are getting stronger from riding my bike more and swimming more, since i have hit 13 my parents allow me to go further from the house and for longer periods. So my legs are getting strong

Yes, your leg, arm, shoulder, and chest muscles are the ones that naturally grow stronger during a boy's puberty because of testosterone. But if you want to see definition, you'll have to do exercises. However, once you have testosterone it's a lot easier to build muscle this way.

I think after the onset of puberty, my muscles got bigger and more defined. Although I would like more.

Muscle growth will only improve by working out and doing sports. Swimming is the only way to work out all muscle sets and has to be done on a daily basis. Other sports are also beneficial imo depending which muscle bulk is needed.

i started working out when i was 12, then i started getting taller but i dont think it was the working out, just starting puberty i guess

My parents would let me lift weights until I was 14. They were concerned about stunting my growth.

I've been doing lots of exercise ever since I was a kid, so I did have some muscles. But starting puberty definitely made them grow faster and be more noticable

But didn’t you say that you actually started puberty on the early side?

Chris 16 wrote:

Muscle growth will only improve by working out and doing sports. Swimming is the only way to work out all muscle sets and has to be done on a daily basis. Other sports are also beneficial imo depending which muscle bulk is needed.

And don't forget to release the trained sharks