This. Plus gratitude. Stop being an entitled little shit and really look around you at the world. If you're reading this, it means you have at the very least a computing device and an internet connection. Which means you're better off than most of the rest of humanity. Try to be grateful - truly grateful - at least once a day. Send that shit out to the universe, and you'll get it back in spades.
You have to be able to make yourself happy. Using people, drugs, sex, money, whatever... to make yourself feel good is fine, but at the end of the day all we have is our own perception of ourselves and our lives.
After getting a degree in philosophy and just generally struggling with this question for years, I really think this is the answer.
That, and trying to live a meaningful life. A life that's meaningful to you.