New father runs a mile a day for 100 days and reports body, fitness and mood changes

Zack Telander, a Texas singer-songwriter and new father, said he ran one mile every day for 100 days and experienced noticeable changes to his body, cardiovascular fitness and mental wellbeing.

Telander told Men's Health he launched the challenge on June 1 after the birth of his daughter, setting a simple target: run a mile each day and try to shave about 10 seconds off his time on successive attempts. He said his first mile clocked in at about 9 minutes, 43 seconds and that the streak grew from a 22-day run into a 100-day commitment.

Telander posted a before-and-after video from day 100 to his 200,000 Instagram followers and wrote, "100 days of running in a row. I ate more, slept less (we had a baby) but managed to change my body a little bit. Here's to 101!" He said the biggest reward was an improvement in mental wellbeing, and that his running pace, training volume and recovery all improved over the three months.

The musician, who has a background in heavy lifting, said the daily runs changed his approach to weight training. He described running as becoming a priority and said he often lacked the energy to lift after his runs. He also described workouts that included high-intensity sessions, saying he at one point ran 12 repetitions of 400 metres at a brisk pace with only one minute of recovery between intervals.

Telander said motivation was a recurring challenge and that personal accountability helped him maintain the streak. "There were definitely days where I didn't want to run," he said. "The one thing I kept telling myself was 'you know you didn't run.' I could be like 'well no one is going to know if I didn't do one of the days here'—but I would know, and that made me put my shoes on." After 100 days, he said he planned to continue running to preserve the endurance he had built.

Health experts say regular running can produce measurable benefits for cardiovascular fitness, lung function, bone density and mental health, and that it can contribute to weight management when combined with a healthy diet. The World Health Organization recommends that adults get at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic physical activity per week; running is generally classified as vigorous activity.

At the same time, clinicians and exercise scientists have warned about the risks of rapid increases in exercise volume or intensity. Short-term, intense fitness challenges can increase the risk of overuse injuries and may trigger inflammatory responses that slow recovery if not balanced by adequate rest or nutrition. Overtraining can also affect sleep and energy levels, factors Telander said were affected while he adjusted to fatherhood and daily runs.

Physical inactivity remains a major global health concern. The WHO estimates that about 2 million deaths per year are associated with insufficient physical activity, and public-health analyses have linked sedentary lifestyles to heightened risks of heart disease, type 2 diabetes and certain cancers. In many countries, prolonged desk work followed by sedentary leisure time contributes to these risks.

Telander's experience illustrates both the potential gains from consistent aerobic exercise and the trade-offs individuals may face when they alter their training priorities. He reported a more toned appearance, faster recovery between efforts and increased capacity for sustained running compared with his fitness at the challenge's start. He said he no longer felt limited to a mile or two at his target pace and intended to keep running rather than return fully to the lifting-focused routine he followed previously.

Experts say gradual progression, attention to recovery, and listening to pain or fatigue signals remain important for people seeking similar changes. For many adults, integrating regular aerobic activity such as running into weekly routines can yield cardiovascular and mental-health benefits, but clinicians recommend tailoring volume and intensity to individual fitness levels, medical history and life circumstances.