Being naturally too skinny, how do I gain weight? 115lb guy?

Try eating loads of protein foods, like egg or bread, and make sure to have big breakfasts! Also if you want to keep fit as well, you could try sit ups at home or maybe even weights and press ups? (if you are into that sort of thing)

make it a point to use the steps whenever possible use the bathroom on a different floor at work take the stairs at the bus station the airport or the mall

Use less salt in food

Just eat and sleep

go out dancing or take dancing lessons

sometimes even sleep is not as restful as it can be