So, what makes one of the world's richest men happy?
While you might assume the answer might be "having lots of money," it's not necessarily the case for Bill Gates.
Gates said in a March question-and-answer session on Reddit that while money has made him happier overall, because he doesn't "have to think about health costs or college costs," being rich isn't the sole reason why he's happier now at age 63 than he was at 25.
Gates talked about four other ways he is happier now more than ever. These don't seem so hard -- you could even follow suit. Here's how:
He has a giving mindset
The Bill and Melinda Gates Foundation is the world's most affluent charitable foundation, and Bill Gates said the foundation's efforts to combat issues such as poverty, disease and hunger around the world have made a difference.
"Our biggest achievement is working with partners (including rich government-aid groups like the U.S. Agency for International Development and DFID) to make sure all the children in the world get vaccines," Gates said during the chat. "This is a big part of the reason that deaths of children under 5 (have) dropped from over 10M when we started to less than 6M now. GAVI is the name of the group that was created -- all the donors to GAVI deserve huge thanks (mostly from the voters in the countries who gave)."
Researchers have discovered that even thinking about doing generous things has mood-boosting benefits, according to a Time article.
Gates also talked about what more is left for the foundation to accomplish.
"The goal of the foundation is that all kids grow up healthy -- no matter where they are born. That means getting rid of malaria and many of the other diseases that affect poor countries. It should be achievable in my lifetime."
Gates didn't hesitate to respond to one question about what makes him happy.
"Some recently said that when your children are doing well, it really is very special, and as a parent, I completely agree," he said.
Treating your body right can reduce feelings of stress and anxiety, according to Harvard Health Publishing.
Gates said he is an avid tennis player, and one of the features of his house is a trampoline room for his kids.
If you've made a commitment, you shouldn't take that lightly, and Gates said it's essential to make sure you honor those commitments.
"Sometimes, following through on commitments to yourself like doing more exercise also improves your happiness," Gates said.
Through it all, Gates said, he has a much different perspective on happiness as he has aged.
"When I was in my 30s, I didn't think people in their 60s were very smart or had much fun," he said. "Now I have had a counter-revelation. Ask me in 20 years and I will tell you how smart 80-year-olds are."