@Toronto2014: Well, first, you know the FIT principle, right? In order of importance:
F – Frequency – how often you work out.
I – Intensiity – how hard you work out.
T – Time – least important is how long you spend on each work out.
You will, obviously, want to do resistance training for your upper body. Low weight, high reps – no secret there. That can be accomplished by using wrist weights, or dumbells, or what-have-you when running, either on a treadmill, or over ground.
I would also work in these exercises, 30+ reps, 3 sets, don’t have to do every one, every day, but work them all in periodically – variety is good in many, many ways:
One arm row. Seated row. Military press. Dumbell flyes, lat pull downs, hammer curls, bicep curls. Sit ups at various angles – i.e. rotating your chest left and right when doing sit ups, to target your obliques (side muscles) on both sides. tricep pull-downs, single dumbell overhead raises (also a tricep exercise), lateral dumbell raises (for middle shoulders, and also your arms as stabilizers).
You should be able to get diagrams/videos of those with a google search; they’re pretty standard. I would aim to do some kind of work out 5 times per week. Even if sometimes you feel crappy, and only work out for 10 minutes, do everything you can not to skip it.
Swimming is GREAT, and so are yoga and pilates, and all those dance-based exercise classes. remember that resistance training, and the fast movement cardio/aerobics/whathaveyou, are high impact, and will increase your bone density, as well as your muscle mass, so you will add weight in both of those ways. But, your goals are to be healthy, and to improve your upper body aesthetically, so you can judge your success by how you look and feel.
Try to rotate through different resistance exercises continously, so that you are also keeping your heart rate up, which will help with burning the fat.
Throughout that resistance training, you will also burn fat, and lower your % body fat, which shuld e 30-ish percent for most women, if I remember my ex phys correctly. you can double check the stats by hopping to a University library and checking a text book.