I use that timetravel trick as well; I never thought I was old (I like getting older so far; so many doors just open that were closed before), but yeah things to tell your younger self; do not hurry so much. Make 10 year+ plans when doing things. I always hurried thinking something would end; I have been running companies since I was 15 and, for instance, the first company I co-ran with my uncle, made educational software for MS-DOS and later Windows 3.11 and then Win95 etcetc. I was in hurry because I thought first MS-DOS would go away and then that Windows apps would go away because web. The software I made then sells well still; it's now over 25 years old... Why did I hurry/worry?

Things I thought that would end, like the CMS market 16 years ago (a market my company thrived in) didn't end. They became bigger. If I would've not hurried, I would have less stress at the time and probably be running on a larger scale than that company is doing now. You cannot stand still and for some parts there needs to be a sense of urgency but it doesn't change that much in most markets. Currently I use that to tell my colleagues we need a 10-year plan, not just a 3-5 year plan.