If you are one of a number of people who are slender, with thin muscles and find it hard to gain weight, you might be classified as an ectomorph.
Short upper body, long arms and legs, with long narrow feet and hands, they possess very little body fat; have narrow chest and shoulders, with long, thin muscles.
These folks are usually slender all their life and whether tall or short, will have long extremities.
How does an ectomorph get to look like Brad Pitt, Will Smith or Frank Zane? Skip the fancy workouts and get moving on the basics.
You can start by learning the proper way to execute squats and deadlifts.
The key to squatting and deadlifts is form.
The key to getting good form in the squat relies on stretching, position and breathing.
Stretching will get you limber enough to get the correct form during the movement.
The stretching that needs to be done is for warming up your muscles and ligaments.
Warm up your: -Calves  -Hamstrings & Lower Back  -Groin       Breathing - take one to two breaths between early reps.
Proper breathing is important in the execution of both exercises.
Taking the bar in a power rack, place the bar low on the traps.
Step out from the power rack.
Using no heel support, with a shoulder wide stance - keep your head up; lower yourself slowly until your thighs are parallel to the ground.
In this bottom position, pause momentarily as you DRIVE your feet into the ground to get back up.
In the bottom position your back should be straight but will be slightly bent forward.
The less the bend forward, the less danger on the back.
As you rise, your head up and this will help keep your back straight and near upright.
Do this with high reps for best effect (15-20 reps).
Start off with just the bar.
Practice the squat and the dead lift twice a week, for 4-5 sets since the weight is so light.
Make a very serious effort to get your form right and stretch as outlined above every day to get your muscles and ligaments limber.
The deadlift - Stand before a barbell on the floor or a Smith machine.
Keeping your legs nearly straight, slightly bent your knees, then bend at the hips, while keeping your back slightly arched.
Don't hunch your back, you'll end up hurting it.
Now bend over just enough to pick up the barbell.
Your palms should be faced away from you, but they can face forward.
  Keeping your legs fairly straight, with your back slightly arched, and your arms nearly straight; stand up straight.
When you do the action, avoid locking out your elbows, but don't bend arms, either.
You'll be pulling the weight up as you return to your start position.
Repeat the movement until you completes a set.
Add five pounds at every workout and keep perfect form.
As the weeks pass, you will need fewer sets 2-3 per workout.
You'll then increase your reps (up to 20).
These two exercises will get you growing mass in six weeks.
Food is 60% of your effort You're going to need a lot of food in order to support the bulking phase.
Your muscles will need lots of fuel to stimulate growth hormones.
Eat six meals a day and drink at least a gallon of clean filtered water a day.
Eat only nutritious foods.
Whole wheat bread, potatoes, lean-beef, fish, chicken, non-fat yoghurt tofu (in small amounts) and whey protein are great sources of nutrients.
Go for nuts and legumes as well.
Add olive oil and apple cider vinegar to your salads.
Monounsaturated fat is necessary for muscle growth as well.
Try to junk-food off the menu if possible.
You should be able to see substantial progress within four to six weeks.