HDD wear...and tear

There is a light next to battery status that flickers on and off. It seems to be about HDD activity(it flickers very rapidly aftet boot during which time PC is not responsive...busy?). It also flickers as rapidly during any scanning...like, anti-virus, sfc /scannow, diskcheck, defrag, disk cleanup, system restore, etc.

I tend to do these scans very often, easily several times a week. I also turn off PC at least once daily. I might even be trigger-happy with SR at the slightest suggestion of malfunctions. Am I wearing down my HDD?

With normal use a Hard Drive is expected to last anywhere between 5 and 10 years.
Turning off the computer no longer extends the life of a hard drive. It years ago but these newer hard drives are meant to be used and turning off does not prolong the life. In fact, turning the computer off is the reason it is busy when you boot. It is performing the tasks it would normally due when not busy (in your case turned off). You should boot the computer, about once a week, so that any errors can be corrected at boot.
Bottom line, with today's modern hard drives just be sure to turn off properly, and this is the best thing that you can do to keep your hard drive in good shape. I have also heard, that overuse of chkdsk (with both boxes checked) does hurt the drive.
You may want to download the free crystal disk to check on the condition of your hard drive and to check its progress
CrystalDiskInfo - Software - Crystal Dew World