I've never really been motivated to get fit, than I am now. I just want to feel confident about my body, 'cause I'm damn skinny. I just want simple routines that I can do in a weekly basis (with or without machines) I weigh at about 110 lbs. Height is 5'7, and 16 y/o. It's summer here so I wouldn't mind paying to go to a gym. My cousin recommended me to take Multivitamins to gain weight, is this a good idea? Any advice you can give me is greatly appreciated.