Timed Tasks

Doing pretty good setting timers, of which I have several, for 18 minute and 18 seconds, mostly.  Sometimes 22 minutes and 22 seconds, which offers a compromise for aerobic treadmill benefits and protection of injured joints.  Rest and internet surfing does well with 25 minutes and 25 seconds.  But 18/18 best assesses my ability to sustain interest in what I am doing or defining an escape point for activities I must do but don't really want to.  This is not Flow, which I also experience for a few things, but the timer defines sessions to pursue my Daily Task List, and with considerable success.