I had gynecomastia form at the age of 13, it was simply put, horrible. Years of torture at school, social events etc.
Excercise and weight loss ( I was a fat kid, but the gyno was very disproportionate to my tubbyness ) did little/nothing to alleviate them. Last resort I had them removed by a plastic surgeon, it actually took 3 surgeries to get it all out. Pretty nasty, but it had to be done.