Excuse me? Yep, one runner found out just how treacherous the gentle pastime can be when he was set upon by an 80-pound mountain lion.
But seemingly unphased by the attack, the jogger calmly dealt with the cougar, suffocating it with his bare hands.
According to a statement from Colorado Parks and Wildlife (CPW), the unnamed man was making his way down a trail run on the West Ridge Trail at Horsetooth Mountain Open Space, in Fort Collins, when he heard noises coming from behind him.
Spinning round to see what was making the noise, he was confronted by a mountain lion bearing down on him, before it pounced, biting his face and wrist.
Whereas most people probably would have froze with fear, the mystery jogger was taking no prisoners, grappling with it before killing the lion.
The unnamed man suffocated the cat after the cat attacked him during a run. Credit: PA
In a statement from Mark Leslie, the manager for the Colorado Parks and Wildlife Northeast Region, he said: "The runner did everything he could to save his life. In the event of a lion attack you need to do anything in your power to fight back just as this gentleman did."
Perhaps less surprising however, the courageous runner did sustain some serious injuries during the attack, but was able to get himself to hospital to be treated and they were not life-threatening.
Ty Petersburg, the area wildlife manager for Colorado Parks and Wildlife, said in a statement that despite this incident, cougar attacks on humans are rare and the animal's 'hunting instincts were triggered by the runner'.
He said: "This could have had a very different outcome."
The CPW said the mountain lion was a juvenile male, and a necropsy has been performed.
The agency wrote on Twitter: "After additional investigation, including examination of the lion, we have confirmed the victim's account that he was able to suffocate the animal while defending himself from the attack.
"We can also confirm the lion in this case was less than a year old, and we may be able to determine age a bit more tightly in the final reports. The cat also tested negative for rabies, which is very welcome news."
As a result of the attack, The Department of Natural Resources in Larimer County, has said stepped up patrols at Horsetooth Mountain Open Space.
Featured Image Credit: PA