Every training session should have, at the start, a main lift. And really the first, main lift, is what really matters. A typical work out may be set up like this:
Squat
leg curls
rows
chins
But sometimes I think it's best do just perform the main lift and just leave.
Back in the old days, circa 1989, my training partner and I, Jimmy Anderson, would squat and leave all the time.
In fact, I can't recall ever doing anything else on squat day. Oh yeah, we always listened to Charlie Daniel's while we trained and ate biscuits and gravy at Hardee's immediately afterward.
I used to like to just squat and not even take the weights off of the bar. And leave them like that for awhile. I am not sure why. I'd always go back and take them off later.
(On another note, I have always admired minimalists. No phone, cable, no frills. And from the 1800's, the Mountain Men, recluses.)
So I was thinking that when you do that, just perform the main lift, that you are reaching your minimum for the session. Like you had to at least do that, and then you have given yourself permission to end the workout. I also have a rule regarding minimums when it comes to running the hill near my house. You have to do ten in order for it to count, for it to be a real training session. Any less, and it was just a warmup.
And I have to admit that I have pretty much always just done the main lift. Damn, most of the other stuff is just so damn boring. C'mon, man! Lat pulls, pushdowns, extensions, blah, blah. Now bent over rows are great, and one arm rows and some shrugs. After that? Just pull, squat, press. Fun!
You can do it with reps also. I have to get at LEAST 5 on this set, you decide. And then any reps after that are just bonus.
It's like writing a book (I have to get a certain amount of words in each day)or daily tasks to be done (I have to do these three things at least).
And if you feel like crap- sick, way under the weather, done, just say to yourself that you can do a few sets of benches and you are finished. Anyone can do one exercise, right?