How do I not be so gangling?

So instead of actually ANSWERING the question, you are told that "You neglected to mention your age".

No matter WHAT your age is, NOTHING is going to alter the size of shape of your growing bones - that's all down to your genes - but the sports medic at your local gym (assuming you're old enough to join) will be able to advise you on HOW to walk or even hold yourself up so that you DON'T look like the gangling youth you sound like - or show you how to exercise. If you can't join a gym, talk to your PE teacher about it instead.

funny stuff.

there is nothing to drink to make your arms longer.

you dont say how old you are.

but as you get older,not only will you get taller,but your body will get bigger as well.

your shoulders and pelvis will get broader.

You neglected to mention your age.