When you start a resistance program your muscles are experiencing a new change—a neural adaptation to be precise. Your muscle fibers start to fire and become stronger. This occurs during about 8-20 weeks of your resistance training program. After this time is when hypertrophy (strength gain) occurs. It takes on average about 14 weeks for hypertrophy to occur. So, why am I writing this? Because it is important that we incorporate resistance in our workouts. The ACSM guidelines for resistance training suggest performing weight lifting exercises at least 2 days a week. 1-3 sets of 8-12 reps of 8-10 different exercises. More information can be found here or at www.acsm.org . In High School and College we have the opportunity to take a weight training class if we so choose. The only problem with this is that you start gaining strength when the class ends, so we just need continue lifting even after your class ends—make it a part of life!
Challenge: Start doing resistance training now. It can be really simple. One way is simply by doing push-ups every morning/night. Start with 10 and increase each week. In 20 weeks you will be stronger!
Other Ideas if you don't live close to a gym:
1- Look in your cupboards--Use cans of beans or filled waterbottles as weights.
2- Buy a resistance band and do leg exercises with it.
3- Find a couple of heavy rocks to substitute for your weights.
4- Invest some money in some free weights. I think they are about $5 at Walmart.