How can I stop being chubby, and become leaner?

There is no such thing as big boned. Anyone can look great if they work at it hard enough. I know it might suck and cliche but the way to get good looking is to work out, run, and eat less calories. A body burns about 2000 calories a day, so if you eat under 2000 and work out everyday you will lose weight. Honestly, if you want it you have to push for it and not cheat. Good luck.