Why would anybody desire to gain weight? If you have not been under weight and know what it is like to be picked on as the skinny guy, or unable to protect yourself from somebody, then you would not understand.
You can feel a lack of self-assurance in yourself, also when you see all the other guys that are built larger physically; you just want to be bigger.
If you fit this description, you are most likely a hardgainer.
Someone that is very skinny, and can not seem to gain weight by any means possible.
You were born skinny and have given up hope of ever putting on a lot more weight.
It is no use giving up if you really want to get bigger.
You just have to take in more calories than you expend and work out in a way you may not be accustomed to.
The idea is to do exercises that will boost your hormones that will allow your body to absorb all the extra calories you are eating and grow.
If you are not working out with weights, now is the time to start.
If it is something new to you, take it easy at first so you gradually get into shape.
Later you will start a way of lifting that will blast your body.
When you get into your body blasting workouts you will be using the squat as your main exercise.
The squat is the best whole body workout you can do, and if you want to gain weight you must use this.
If for some reason you can not do the squat, your next best exercise is the dead lift.
This exercise along with a few others and taking in many more calories will gradually have you gaining weight.