I had been volunteering at Town Lake Animal Center for two years when I met Felix, one of the many young, energetic, dark-colored pittie mixes at the shelter in 2010. His hyper kennel manners—nonstop spinning, bleeding "happy tail," and frantic yelping—made him a tough sell to potential adopters. I was training for a full marathon at the time, so he joined my running group for our twice-weekly outings, easily covering ten-plus miles at a time, which helped calm his kennel manners.

During our three months of marathon training together, we bonded intensely, and I finally gave in and adopted Felix, my first dog as an adult. During our nine years together, we've road-tripped more than 5,000 miles through the United States and Canada, hiked some of North America's prettiest peaks, fostered fifty-plus kittens, and couch cuddled through countless Netflix binges. At eleven years old, he is still spry and the World's Best Running Buddy.

Felix advises everyone to skip the gym and adopt an Energetic Shelter Dog!