Q: hey mike i need to lose 30 lbs in 4 months should i only do cardio or should i also use weights thank you

A: I would certainly use weights in addition to cardio. By themselves weights only make your metabolism higher and help you burn calories faster! What goes wrong for some people using weights is that the high metabolism makes them hungry and they start eating everything in sight -- and of course gain weight! If you have a firm control of your diet, weight training will only help you achieve your goals faster.

Your goal of 30 pounds in 4 months is a bit faster than I usually recommend, but is not impossible or unreasonable. You will need a good diet, in addition to exercise program, so make sure to read my Nutrition article as well.