I'm 34 now. I've dealt with some heavy stuff. Lost my parents and a sister in a car accident when I was ~20 years old.
I agree that the future comes faster than one might think, which is why I'm in such a hurry to achieve my dream future before I'm 40 years old, so I got still plenty of time to enjoy it. My little sister certainly didn't get the chance to live her dream future.
The trick is that your calling may change -- many children young folka grow to desire children, many lonefolk grow to desire a partner or would be happier with one -- so it helps to prepare for potential changes in your motivations and desires. Saving money is a great way to prepare to change. As is investing in a marketable skill.
Since then I've spent a lot more time thinking about what I want to be doing: work has been slack so I've had fewer chances to see how I now am decomposing software. But I've started to enjoy programming again :)
I'm guessing you're relatively young. What I wished I'd learned earlier is the future comes faster than you think, and the earlier you start planning and saving for it (partner, children, ill health) the easier it is.