I don't believe life has meaning outside of what it means to people and other life forms. That is, in a universal sense, one's life has no more meaning than any other physical event.
That said, there is still room for plenty of meaning. Ultimately each individual should find what is meaningful to them. This is often culturally given, and always culturally influenced. Some people's lives have meaning because they love to play pool, others help the needy.
Personally I believe a meaningful life is one that is happy and good. I have lots of ideas about happiness, but I want to talk about goodness.
Being good, for me, means maximizing your potential for affecting good change in the world, at the largest possible scale. That means don't serve soup in a soup kitchen if you can run the soup kitchen, don't run the soup kitchen if you can effectively lobby for more soup kitchen funding, and don't lobby if you can be president. I think people should push the envelope of the scale of the change they affect until they reach their limit. That is, they fail. Only then, I believe, do you really know what your potential is. Usually, with that attitude, you're capable of more than you might have thought.
For me, I'm talented at science, and I believe AI research is the most important thing in the world. Every time I think of something else that might be more important, I note that that problem itself would not be hurt my more intelligence. So in my life I bust my butt every day trying to make the world better by working hard at AI. I only have the energy to do it about 8 hours per day, though, so in my spare time I metaphorically recharge my batteries by relaxing in the most productive way I can-- I make art, which makes the world better and gives me energy.
These thoughts influence the decisions I make moment to moment every day. I often ask myself: is this the most important thing I could be doing right now?