The bottle says that the tablets contain 600mg each of
"N-Acetyl-L-Cysteine."  I just took one, on an empty stomach, as the
bottle suggests.  It also suggests taking one to four tablets a day, "or
as directed by your qualified health consultant."

One of the first things that really worried me (recently) about my
health was that I found it hard to wield a hammer overhead.  When I was
young, it was never a problem.  I could keep it up all day.  But one day
about six months ago (after not having done that kind of work for
years), I found a muscle in my arm getting sore very quickly --
alarmingly so!

The quoted text from that article from newsrx.com (which I can't find
online) was the first hint to me that N-acetylcysteine might help.  I've
never heard of "fatigue therapy" before.

I hope they're not going to patent that information.  There's been a lot
of controversy about such things recently.  (Michael Crighton
contributed an op-ed essay to the New York Times in which he illegally
divulged a simple scientific fact, if I recall correctly.)

Incidentally, I've done a few more sets of pushups since, and though
this transient muscle soreness problem seems to come and go by itself,
it's definitely gone now.