On your off days, make sure you relax. Intense training sessions should be kept to a maximum of 3-4x per week. It’s imperative to use the other days to rest and recoup. Is it okay to insert some low intensity cardio if you so wish? Sure. But you needn’t do it daily. If you’re training hard on the weights 3x per week, I’d say you should do no more than 2 cardio sessions for the week. Always take 1-2 days for complete rest; sit on your rump and chill out a bit.