Being slim is a great advantage. Thosev who laugh at you are hiding their weakness. So. don't be concerned about slimness. As age will progress weighr is going to rise. As regards weakness. It is not well defined. If you mean physically less strength, compared to others who are equivalent in your age & height, then let me tell you strength can be fully developed. There are exercises for that. You have to systematically go about it.If you do that your slimness will be an advantage. You also have to focus on your diet, have adequate amounts of proteins. Please visit me after having gone through my profile.

Send your physical parameters like ht..wt..bmi...to advice further