In terms of physical activity, running was the ability to move faster than one's typical gait, and exerted more energy than one's normal speed. The Doctor was noted to have spent a great deal of their lives running, accompanied by their companions. Indeed, while introducing the Tenth Doctor to his daughter Jenny, Donna Noble observed that he "[ran] a lot." Jenny quickly grew to "love the running" just as her father did. Departing Messaline, Jenny noted that, among other things, she had "an awful lot of running to do." (TV: The Doctor's Daughter)
Seriously, there's an outrageous amount of running involved.
Saving her from the Autons at Henrik's, the Ninth Doctor introduced himself to Rose Tyler by guiding her to "run for your life." (TV: Rose) Following his regeneration, the Tenth Doctor noted that the very first word he said to Rose was "Run." (TV: Children in Need Special, Rose)