im a 14 year old guy and one of my new years resolution is to gain more muscle as i am quite skinny. as i have no money to spend at the gym, i thought that i could do home workouts like sit ups and press ups. i own a wii fit, which i find can tire me out but im not sure weather it does the trick. i own a kinect for xbox 360 and saw "your shape: fitness evolved" which looks quite good, played a demo. this can focus on YOU specificity and can target certain body areas such as abs, arms which are the main places i want to improve. is this a good purchase, do they work?