How can i be happier and more self-confident?

Practice: Understand that you have a choice of what to focus on or emphasize. Just as you can switch tv channels, you can also change what you place your attention on. It can also help to be more scientific or fair with the use of your attention. Give equal time (or more if possible) to appreciating, being grateful, celebrating vs. Complaining, resisting, rejecting. This probably will help.

Stay active: Exercise is a great way to relieve stress. Your body releases endorphins during exercise, which can help you feel calm. If you exercise 30 - 60 minutes a day, your stress levels can improve. When stressed, take 5 slow, deep breaths with your eyes closed, then roll your shoulders forward 5 times, then back 5 times. This will slow your heart rate and release tension in your neck and shoulders.