In the world of fitness, there's a nifty scale called Rate of Perceived Exertion (RPE) that goes from 1-10. Personal trainers often use RPE to gauge their clients' efforts during or after a workout.

Journal of Consumer Research, Vol. 30, No. 4 (March 2004), pp. 519-533 (15 pages) Increasing the actual variety of an assortment has been shown previously to increase the quantity consumed. We show, ...