Hi,
I am a healthy 26 y/o male from India, I am 6 ft in height and weigh only 135 pounds, I have been trying to put on weight for some time now (past 3 years) but have been very unsuccessful, I have been skinny all my life and I wish to be healthier and weigh at least 175-180 pounds, I eat a lot of white rice and have meat (chicken and mutton), fruits and green vegetables in my food intake but still my weight or body mass does not seem to increase, but this in turn make me have large bowel movements more than once every morning.
I have read some forums and this could be a thyroid issue or I need rigorous workout sessions. I have tried weight training but my body does not have strength to do it and I get easily tired of it.
I need some advice on how to start tackling these health problems as I do not wish to continue looking and feeling like this.

Try doing cardio workouts, they improve your lung capacity and make your heart stronger... maybe those are the reasons you get tired so easily.