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.
Indeed, the Tenth Doctor claimed that he had never stopped running since he looked into the Untempered Schism as the First Doctor, at the age of eight. (TV: The Sound of Drums) Throughout the Doctor's lives, much of this running took place along corridors. (AUDIO: Relative Time)
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." Soon after, he recalled an incident when he and Rose were, in an alternative to running, forced to "hop" for their lives. (TV: Children in Need Special, Rose)
The Thirteenth Doctor considered herself to be an "expert" on running, both towards and away from danger. She believed that running was sometimes the bravest option, as an act of defiance and a proof of agency. To the Doctor, opting to run away in the face of adversity was itself a radical choice, and a far better option than giving up and letting the "monsters" decide one's fate. (COMIC: Hidden Human History)