Heat is the thing that ages hardware
Sustained heat is hard on batteries and on the paste between a processor and its heatsink. Most of it comes from blocked airflow.
Keep vents clear, do not run a laptop on a duvet, and clear dust from the fans once in a while. On an older laptop that runs hot and loud under light load, fresh thermal paste is a modest job that can drop temperatures noticeably.
Charge habits, without the folklore
Lithium-ion batteries age fastest when kept at a full charge in a warm place, and when run flat repeatedly. Sitting around the middle of the range is easiest on them.
Both major platforms now manage this for you — optimised or adaptive charging holds at a lower level until you need a full battery. Leave it enabled and stop thinking about it.
Full-cycle “calibration” of a modern battery is unnecessary.
Leave the drive some room
A nearly full SSD slows down and wears faster, because the drive has less free space to work with. Keeping a reasonable amount free is one of the easiest ways to keep an older machine feeling quick.
Updates, backups and one good case
Security updates are what keep an older device safe to keep using, and they cost nothing.
A backup turns a dead device into an inconvenience rather than a disaster.
And most cracked screens were preventable: a case and a screen protector cost a fraction of the repair, and they protect resale value as much as the device itself.