Where I live, we have access to rudimentary time travel. It's enough so we can send a small piece of ourselves back in time 10 years for a few seconds - just long enough to write one word on the arm of our past selves.
It's also customary to have this word tattooed later, as the process only spares the ink without leaving a trace memory of any kind. The words are deemed important, and it's almost taboo to not have them permanently marked on yourself.
Except, the first time you can travel back to write a word is when you're 30. Which is rough, since I was diagnosed with clinical depression in my late teens, though it was likely a part of me years before. Fortunately with the help of therapy and medication I lasted until I was 20.
I woke up, eager to see what word I would have on my arm. Looking down, I saw what would keep me going for at least another ten years:
"LIVE"
From that moment forward, I did my best to keep a positive attitude. Through college I volunteered at every chance, and though it took me a while, I eventually graduated with a degree. My parents were thrilled, and things were looking up. I got an internship at a local start-up, started dating a girl I knew from school, and would make sure to look at my arm at least once a day, as though to say "I will."
When I was 26, my girlfriend dumped me. It hurt more than you could imagine, and the depression came back in full force. It affected my job, and I was eventually let go. I wound up moving back in with my parents, which didn't help anything but I had little choice in the matter.
There were several times I thought about ending it all. But every time, I would look down at my arm and see that four-letter word that always kept me going. Thinking on it, I realized I would be in a better place in my 30s, enough so that I would make sure I'd use the one word to keep my past self alive to see it.
Things turned around again when I was 28. I got a new, much better job, and could finally afford a really nice one-bedroom apartment in the city. My colleagues and I got along great, and I wound up dating a coworker's roommate for a while. It didn't last, but I was back out there again, feeling better. The depression retracted, albeit slowly, but it was enough to get me to 30. And, like my future self had done before me, I inscribed "LIVE" on my 20-year-old self's arm.
The next day I woke with a smile, pleased with my work to help my past self and obsessively curious as to what new word I'd have on my arm this time.
Only, there wasn't one.