As others have said, you just sort of live with it and it more or less becomes routine/normal.

At 19, I was diagnosed with Barrett's Esophagus, which is when you've had heartburn so much that the lining of your esophagus starts to mutate as a protective measure and develops cells similar to the lining of your stomach. The cell mutations make you predisposed to developing esophageal cancer, so I have to get it biopsied every year or two to keep an eye on it. Rarely fatal, but also usually diagnosed after the age of 50, when there are other age-related issues that are more likely to get you first. And you basically have to take a super high dose of heartburn medication forever (which doesn't fix it, but prevents it from getting worse), which causes it's own issues.

A few years after that, central sleep apnea[2]. Which is a neurological form of sleep apnea, where your brain just randomly decides to stop telling your body to breath. It's not due to physical obstructions like obstructive sleep apnea, so very little you can do to improve things.

Also in the interim, I was diagnosed with a urethral stricture[3]. Which is where scar tissue in your urethra cause a blockage and prevent you from being able to urinate. Scar tissue never really stops growing, so periodically I have to have a surgery to remove the scar tissue that's built up, wear a catheter for a few weeks for new scar tissue to grow, and then wait until it gets bad enough to necessitate another surgery.

All three of them are chronic, albeit not terminal. Although the first one makes you pre-disposed to esophageal cancer, which doesn't exactly have the best survival rate. Dwelling on any of it can be overwhelming, so eventually I just stopped doing that. It is what it is, all you can do is accept it and move on. From a practical standpoint, it just means:

- Substantial budgeting for healthcare. Although I can time it to an extent to optimize things, I'm looking at a minimum of $10-15k every three year cycle in recurring costs even while everything is relatively stable.

- All three of the above were discovered incidentally, rather than deliberately. Two of which happened to be followups to specialists after (unrelated) visits to the ER, and one due to a sleep study I did myself.

- I no longer trust PCPs, due to the above. I had voiced concerns/issues around symptoms for all of the above over many years, and my PCPs had never taken them seriously enough to truly look into the root causes of any of my concerns. I also have a form of eczema that presented atypically, which my PCP basically ignored for ~3 years before I insisted on seeing a dermatologist. Dermatologist couldn't actually tell what it was, but was wayyy more concerned when seeing it as it presented similarly to skin cancer. Turned out to not be, but took a biopsy to confirm. The fact that two different PCPs never felt the same level of concern was mildly irritating and frustrating after the fact. So I'm now far more likely to actively participate in my doctor visits, taking what they say under advisement but following up with my own research and being more insistent on diagnostic tests and referrals. I'm sure my doctors see me as a hypochondriac, but I'd rather have excessive diagnostics and potentially annoy my PCP rather than be surprised by another unlikely but easily tested for issue.

At the end of the day though, it is what it is and I can't do anything about it. And the only real way to manage the stress is to pragmatically accept that and not dwell any more than you have to on it. If anything progresses and gets worse I'll deal with that when it comes, and otherwise I'm not going to let the specter of those possibilities put a damper on things before that.

[1] https://www.mayoclinic.org/diseases-conditions/barretts-esop...

[2] https://www.mayoclinic.org/diseases-conditions/central-sleep...

[3] https://www.urologyhealth.org/urologic-conditions/urethral-s...