It's all about lifestyle Matty, quit smoking ASAP, since the year 2000, nicotine has increased in ciggy's by 11%, with that news it makes it harder to quit, your mouth will test like metal for a month, depending on your mood you might crave one also, it's been 5 months, and if I'm thinking too much, i feel like I want a cig, best bet, all natural, Saw Palmetto, 1000mg Pumpkin seed oil capsules, and garlic tablets to help with chlosterol(chlosterol causes higher testosterone), run twice a day, for 20-30 min., I'm 20 years old and just started living. If you wanna gain weight, work out muscle is heavier than fat, stay away from free weights(trust me assisted is just as good for beginners). If you don't like running, do some kind of cardio, hell i ran around in my own house from time to time, up and down teh stairs. It's exercise with privacy.
And lastly, quitting smoking will highly increase your appetite, I've gained at least 8 pounds since. It's an oral fixation, food is better than smoke. Good Luck
(The boat doesn't sink unless water gets in, don't let critizism in, and you will not only stay a float, you can pull other's out as well.)
~Mike