There are exercises you can do such as push ups that work your pectoral muscles in your chest which will work, trust me...I've been doing them for a long time and i have really strong pecs. Another one is to get a good weight of dumbells and hold them out in front of you with bent arms (think of stretching an elastic in front of your face with both hands) and that will work after a while. You could even get one of those exercise elastics with the handles..that might be your best bet. It's up to you what you think you can handle. You could do something like 15 of these 2 times, 10 of them 3 times, or even more than that a day. Good luck!