Some good advice here:
Five Ways to Become Happier Today | Tal Ben-Shahar | Big Think
1) Accept that you are human and it's OK to experience painful emotions such as loss, jealousy, sadness.
2) Increase quality time with family and friends
3) 30-40 minutes of regular aerobic exercise per week (e.g. walking)
4) Be conscious of your blessings - write in a journal at the end of each day 4 or 5 things you're grateful for.
5) Simplify work and life. Do less. Switch your phone off for a while. Don't respond to emails immediately.