When this is noted as a symptom of different neurological disorders, is there a certain extent to which it's referring to? I don't think I feel weak, but then my mind sometimes plays tricks on me and makes me wonder if I do because I'm paranoid I have something bad. I often try to do things involving my muscles to sort of test myself such as, squeezing a fist, doing exercises, etc. I don't think anything has changed, but then like I said, my mind likes to play tricks on me and thinks that even though I can make a pretty darn tight fist, it tells me it's just not good enough. (Hypochondriac here, fyi).

Like with MS, for example. Is muscle weakness pretty apparent and easy to notice? If you've had it, how did you experience it?

Of course I can't tell you if there is a physical cause for this "weakness" you experience. Because, even if it is caused by a disease like MS, it can be just a slight difference, just a little bit of weakness.
However, if it is caused by a physical disease, most of the time there is progress.
To comfort you, let me ask you this: if you didn't test yourself, would you notice weakness? Most patients don't test themself before noticing they have problems. For me, it was falling down stairs, not being able to open doors, food getting through my nose etcetera.

Your test doesn't seem very good too me. Not good for yourself I mean. It's probably your mind playing tricks, not real weakness. Again, this is just my vision, and Im not a doctor and I cant see you

But there is no harm in visiting your GP, and ask him or her this? There are simple tests to find out if you do have muscle weakness.

I've never not been able to do any of those things you've mentioned. I test myself by making tight fists, and I think I'm squeezing hard? I can see my fingers start to turn white from it, but it also feels forced. I mean, I can do it and squeeze tight but it feels like my muscles are tired haha, like I want to let go. Maybe that's just normal for the human body, I wouldn't know because I never had a reason to make tight fists before so I don't know what "normal" is supposed to feel like. My neuro and pcp have made me squeeze their fingers before, but they don't comment on it and quickly move on the next test so I've always assumed it was fine. I could just be psyching myself out and paranoid.

I think you must stop trying and testing yourself. Dont be afraid, if you can even make it white, there is no weakness. Even if you feel your muscles getting tired, if you're not having problems with normal stuff, there is nothng to worry about. If you can still pick up things, open things, draw stuff, theres nothing to worry about
But I understand its very hard to stop this testing, hope you can do something with my information