Reminder: Inconsistency is Insanity

 If your ideology has contradictions, you are either deluded or crazy.

 I find working out mentally to generally be easier than working out physically, because you don't need any tools and you don't have to worry about decay. Even a single rep matters. Not very much, it is true, but it is a grain of sand that will accumulate with other grains of sand, no matter how long between sessions. Regression is only measurable using expensive, specialized tools.

 However, set 4 is different. Set 4 is hard. You can still do it anywhere without tools, but it doesn't come in grain-of-sand sizes. It requires concentration and tremendous emotional fortitude. This intellectual weight has a minimum size - you have to have already trained to be able to complete even one rep. Further, the individual returns are smaller. 

 Nevertheless, set 4 is possible. You can in fact do reps of set 4 until you can't do them anymore. Set 4 is what truly cures insanity. Set 4 is the final proof against delusion. 

 The truth is all one thing. If your beliefs are not all one thing, then your beliefs are not true.