Your legs may be hiding under wool pants right now, but that's no reason to ignore them. They're not all work and no play though. They put on the power when you ride a bike, climb a mountain, play tennis or even pick up a small child.
Strong quads make every move easier and protect against injuries, especially ones to the knees.
This exercise, the leg extension, is the perfect exercise for strengthening your quads. Do one to three sets with both legs. If you can't do eight repetitions, the weight is too heavy. When you can easily do 12 repetitions, the weight is too light. Remember to breathe.