[Southpaw]

Since health is your main concern, it probably won't hurt to do cardio and weight training in the same day. Heavy cardio works against weight training though, so if you're doing both on the same day, stick to low impact cardio like bikes and elipticals.

Try to stay away from running completely. It's horrible for your knees and it can actually shrink your muscles from the constant impact. If you really like to run, do it on a beach or grass, and not on your weight training days.