Surroundings play a vital role in building your character. If you choose to be with good, optimistic and positive people, you become like them. Always be with people who bring out the best in you. Along with that, you can develop good hobbies like reading, playing musical instruments, playing sports, etc. Meditation is a very important aspect to attain peace of mind. One should meditate every day for atleast 15 minutes. Meditation makes you feel beatific. Whenever you feel sad, you can think about happy memories that will calm you down and make you feel happy.