Don't think too much. Keep working. Excessive thinking can do nothing but stress and waste of time.
Hangout with people who have the same interests / goals as you. If you are offline go online. Hangout does not mean "hangout" literally. I mean spend most of your time with them
If you feel lonely, seek help from your parents.
Do not compare yourself with others. Your body will never look like Kardashian or Brad Pitt. Accept it.
Get the Sun every day. It will keep you going all day. Staying in a dark room all day will greatly reduce your productivity.
Keep a thank you journal for your unpleasant moments. It works like magic! Hopefully!
And lastly — always happy friend! Life is too short!