Plan to have a session of 30 to 45 minutes, 3 or 4 times a week (every other day). It may sound like a surprisingly manageable plan, but remember that during each session you have to do it as intensely as possible. The muscles will definitely hurt at first, but the pain will subside as you get used to the routine. During each session, lift as much weight as you can in the right way. Test your limits to find out how much weight you should lift, doing repetitions with different weights. You should be able to do 3 or 4 sets of 8 to 12 reps without having to lower the weights.