Don't worry about the particulars of your problems. Everyone has problems(and they will often go out of their way to hide them), but the best way to resolve them is to keep working on yourself and try to find whatever lifestyle you are looking for, within the context of being a student. The small positive habits can build up to help you achieve larger results, because at each step you will worry a little less about your life, and feel a little bit freer to take action.

Most of the other suggestions here are based on exactly those kinds of small habits - take exercise, eat well, try to talk to people, etc. Many people enter adulthood retaining major imbalances in their personality, and they tend to find their way towards balance only with the passage of years and effort.