I think that having unimportant-seeming health problems checked out by a medical professional within a reasonable amount of time of them first occurring (from immediately for serious problems, such as chest pain, to perhaps a week or two for things like general aches and pains) is a ridiculously good heuristic to have in general.

One of the things I've done for this is keep a list in Workflowy of minor medical issues. It still doesn't feel worth the hassle to go to the doctor for one thing--"hey I've got this tiny lump on my finger, what's up with that"--but it does feel worth it to say "hey, these are the five things I've noticed in the last six months, can you spend 2 minutes checking each of them out?" If four of them turn out to be harmless cysts and one of them is an actionable issue, the appointment still feels like a success.

I also don't have a very good intuitive sense of the past, with things basically getting lumped into "the last week" or "before the last week," and so I've found it very helpful to be able to say "hmm, this lump that I noticed 'recently' has actually been there for eight months. Maybe I should treat it as permanent instead of temporary" because it's on a list with a date that I noticed it.