aka pick your battles.
And, relatedly, only fixing problems as they become necessary to solve vs. trying to do everything in the order of how interesting it is, or how difficult. A lot of problems just go away if you're successful, and almost all problems go away if you fail to complete earlier goals.
aka "I'll burn that bridge when I come to it"
Things I am better at at 55 vs. 25: everything else.
Seriously.
Magic Johnson (great American basketball player) once described the difference of being a world class athlete at 30 vs. 20: you have to be a whole lot smarter about how you use your body and recover when competing with younger people.
We programmers OTOH get the best of both worlds: the ability to work smarter against a physical and mental landscape that doesn't degrade nearly as fast as a world class athlete.
Frankly, when it comes to work, I can't think of a single thing I "used to do better", not creativity, not work habits, not personal habits, not physical or mental toughness.
I believe that programming, like running, is one of those things where the performance curve can remain flat until retirement, providing you take care of yourself. I'll let you know if it does.
Things I am better at at 34 vs. 25: Not needing to stay up late, or code until the wee hours, and yet accomplishing more.
The same secret to everything else.
But what I'm really trying to ask, is I'm wondering if in ten years the maturity of the average young founder has changed. Are the people who start tech startups at 21 a different type of people than those who started them in the previous bubble? What changed? Where did the arrogance go? Or am I just hanging out with the wrong crowd?
Ummm, what was I saying? Sorry, I forgot. ;-)
Ahem... well based on the fact that we're seeing "startup advice from the ripe old age of 30", I'd say it's more like 30 is the new 60. And my experience in the Valley would seem to reinforce this. :-)
Nothing wrong with betting the farm at 21 & single.
Now, 27 & married, I've found that I'm much better at taking calculated risks without betting the farm.
In Italy until 25 you're just a university student.
But speaking about the future of a country, giving the young the opportunity they are given in silicon valley is surely a good thing.