Hey there, just as a suggestion, weight lifting is great to do, I aam on a certain program and it works well, The key to it is super sets. For example I you take 2 exercises at 2 sets of 10 reps. You do the first exercise for a set of 10, you rest for 45 seconds, then you do the second exercise for a set of 10 and repeat. Its also great to do intervals while you are doing your cardio. I tend to do mine on the bike, but you can certainly do them on a treadmill as well.