A surefire way to build up muscle is to do exercises which involve as many muscle groups as possible or what we called "compound exercises". Execute each repetition with a strict form is the key to building/maintaining muscle using these simple yet effective exercises.

I have decided to install a chin up bar at home and it is a really useful tool as doing chin ups is a good way to build muscle and strength. Good thing is, it is not expensive and you can do it yourself easily.

Here's are some of the simple yet effective exercises you can do and they do not involve weights.

Deep Knee Bends - It builds your thighs, gluteus, hips and great for lung power and endurance. With your feet about shoulder width apart, hold on to the edge of a table of anything stable and while looking up, bend your knees and lower until your butt is just about touching the floor.

Slowly and steadily stand up again using only your legs to lift you, keep your heals on the floor and do as many as reps you can. For some variation you can place your stance wider or closer, or do them one leg at a time.

Calf Raises - Do them on steps or some platform; put your toes on the edge of a step and hold on to something stable for balance. Lower your heals to get a good stretch, then raise up on your toes as high as you can and give it a good squeeze then lower and repeat for as many reps as possible

For variation try them in the squatted down position, one leg of a time or donkey style. Or you can use a dumbbell.

Chin-ups or Pull-ups (My favorite) - This is good for building a stronger back, shoulders and biceps. Grab a bar with an under hand grip and hang down getting a good stretch in the lats, Pull up until your chest hits the bars, lower and repeat for as many. Make sure you do it in a very controlled manner and giving your lats a good squeeze at the top position

These can be easily be done in a park, school yard or on a doorway chin up bar at home. Also try with an overhand grip, with one arm at a time, or even on monkey bars using a parallel grip (palms facing each other).

Push-ups ( Another of my favorite) - It is very good for building chest, shoulders and triceps. Lie face down on the floor hands about shoulder width apart keep your palms turned inward slightly, push-up until your arms are straight and give your chest a good squeeze. Lower and repeat for as many reps as you can.

To make it more difficult elevate your feet. Also, try different hand placements (closer together or farther apart). They can also be done between two bars, chairs or pushups.

Handstand Push-ups (Intensiveperform with care) - This is great for shoulders and arms. Get into a handstand next to a wall, put your toes against the wall for balance, lower yourself until the top of your head touches the ground, push back up and repeat for many reps. Try both close and wide hand Placements.

Crunches ( 6 packs!) - For firming abdominals and reducing stomach. Lie on your back with your legs bent and your heals close to your butt, put your chin on your chest and your hands behind your head. Raise your head up crunching your abs hard hold and then slowly lower again - keeping the tension on your abs throughout the movements.

Lower Leg Raise - This is a great exercise for the lower abs, hip flexor and thighs.Lie on your back and with your both feet together, slowly raise the knee cap towards your chest. Continue lifting your knee caps toward you chest until your entire butts is off the ground.

At this point, just your lower abs a really good squeeze for 1-2 secs and slowly lower your leg back to the ground again for a full good stretch of the lower abs. Perform at least 12-15 reps for 3 sets each time for maximum effects.

Hyper-Extensions - For strengthening your lower back. Place a chair near a bed, while lying face down with your hips on the chair and your lower legs shoved between the mattress and box spring, put your hands behind your head and bend forward at the waist as far as you can, raise back up until your back is straight and repeat for reps.