Well, your Mac really, but I'm sure you get my point.
When I began work (and probably still in some industries) it was common for anyone who operated machinery to stop normal work after lunch on Fridays to clean and run maintenance on their equipment.
Now that things don't need oiling and adjusting so much it's no longer necessary to down tools early on Fridays. Ignoring maintenance all together though, can lead to Mac downtime and, as we know, that always seems to come at the most inconvenient time.
What about your Mac requires maintenance? Well, there's filing and backing up of your digital stuff to begin, and then we should keep tabs on the health of our storage devices, both internal and external, including backup drives. This can be done with Disk Utilty (Applications>Utilities folder), and then, if repairs are required to our startup disk, booting from the Restore partition (hold Command & R) at startup and running Disk Utility from there.
And of course, ensure that your backup is actually happening. The Time Machine icon in the menu bar will tell you the date and time of your most recent backup.
Storage devices have a complex 'directory' that keeps track of where on the device the computer should find the particular file it needs. This directory can become inefficient over time and sometimes become corrupted, causing problems. Disk Utility can handle simple issues but if it fails to repair you'll need a more heavy duty software tool.
Here DiskWarrior is rebuilding the directory on a startup disk that no longer would. Yep, 120 million+ tests!
And then there's the kind of maintenance that requires hardware tools. This is comprised mostly of the removal of dust and fluff from the inside – fans and cooling surfaces. Below are a couple of photos demonstrating the point. A set of fans from an iMac and the cooling fins fully choked with fluff in a 13" MacBook Pro with its fan removed, niether of which have had much recent attention. These are typical of Macs that operate in carpeted or dusty rooms. The cooling fans suck in the environmental detritus and eventually defeat their own purpose.
The main reason these two Macs are disassembled is that their graphics processors had broken solder joints due to overheating.