Authors:

Vary your training, your running partners, and your environment. Only your imagination limits the ways you can spice up your running routine.

Bob Glover, Jack Shepherd, Shelly-lynn Florence Glover (1996). “The Runner's Handbook: The Bestselling Classic Fitness G for begng Intermediate Runners 2nd rev Edition”, p.51, Penguin
Vary your training, your running partners, and your environment. Only your imagination limits the ways you can spice up your running routine.