Personal experience, Re: Treadmill task + "thinking the end is near" strategy. Personally I do the opposite, and pretend I actually have 20 miles to run when in fact it is only 2. That helps me get into the mindset of running for a long period of time and I settle in for the long haul. That way, 2 miles is done before I seem to think much time has passed relative to the whole journey.
Conversely, if I focus on the 2 mile mark (for example) and glance at the meter to see that I've only traveled 0.6 miles, it's quite frustrating. Each successive glance shows a marginal increase towards the goal, adding to fatigue. Better not to watch the clock at all.