Personally I've decided that life is absolutely meaningless, and I've found that to be incredibly liberating. It's helped me to not put so much pressure on myself to achieve (achieve what?) and live more in the present. It's a shame that people who don't find meaning in their life tend to take the opposite tack toward depression. Or others gravitate toward followership to anyone who will tell them how to live. If I could give advice, it would be to not do that. Half the fun is figuring out what's meaningful for you.
Otherwise, there are various clichés. People will say their family is most important and money is meaningless or some variation. I think those truisms are worth the amount of time it takes someone to repeat them, which isn't much at all.
And I love that scene in Fight Club where Brad Pitt is telling Ed Norton that he won't be truly enlightened until he knows, not just thinks, that he is going to die. I wouldn't risk your life or hurt yourself to figure this out, but if you're in your 20's and haven't had any near-death experiences, as you get older, you will DEFINITELY realize that your life is finite and it will change your perspective. There will be a thousand things that in the back of your mind you always have thought you'd have time to do, but then you turn 30 and start to realize that you probably won't. And that you need to start economizing and prioritizing.