My Mestinon is basically what keeps me going. If I forget to take a pill, I notice the fatigue when I'm about an hour over-due. Often the first thing I will notice if I am late is the feeling of a weight on my chest, from the fatigue of the breathing muscles. Then I know I've got to take a pill. Like right now, I'm late for my bed-time pill, and It is rather a strain breathing. Basically what I notice when I take the Mestinon is more a lack of fatigue than a positive feeling of being able to do more, more strength in arms, etc. Does that make sense? Just a the fatigue tends to creep up insiduously, until I realize I've forgotten a pill, so the effect of the Mestinon kind of "creeps" up, keeping me from feeling the fatigue.