When Markelle Taylor served time in San Quentin Prison, he said he found himself when he joined the prison's 1000 Mile Club running group.

After he was paroled after serving almost 18 years for second-degree murder, he kept running and eventually completed several marathons.

Taylor's story is now featured in a new documentary "26.2 to Life." He and director Christine Yoo spoke with ABC News Live about his story.

ABC NEWS LIVE: Markelle, the film begins with a famous quote that says, "The journey of a thousand miles begins with a single step." The quote referenced in the name of the group, the 1000 Mile Club, as you count the distance in not just miles, but years. Tell us about that.

MARKELLE TAYLOR: Yes. Through almost self-help groups and the running combined, I just took one day at a time. And through that process, I was able to create a life for myself and build a community with friends and with the cultures. That's a family bond, it's community, it's family, it's love, it's all those things that I was able to capture in that experience of my incarceration. Therefore, I was able to, from the beginning of that process to the time [of] my parole, was able be free in my mind and heart.

ABC NEWS LIVE: Christine, you not only tell the story from inside prison, but you go into the community meeting with the families and connecting with the upbringing of these incarcerated men in your story. Why was that context important for you?

CHRISTINE YOO: Part of being in prison is isolation. However, each one of these people are connected to individuals, [and] to family members on the outside. So the idea that when we put one person in prison, we put their families also in prison was something that I learned, of course, and something that I felt was very common to the human experience of incarceration.

ABC NEWS LIVE: And Markelle, the audience has taken on this journey with you from your time in prison for second-degree murder and joining the running club to your release and, of course, your journey to the Boston Marathon. What's it like for you to watch that personal evolution?

TAYLOR: It gets amazing [the] more and more I see it. At first, I had my skepticism about it, but then I got used to seeing it, and then it made a whole lot of sense. And just the way she put it together was beautifully masterful.

However, with that being said…my journey to filming that and watching that, it captured my life experience in a way that keeps me accountable and also helps me with my rehabilitation. Even now, whenever I watch it.

ABC NEWS LIVE: And you've returned subsequently to San Quentin and coach runners in the 1000 Mile Club. What's your message for those men, including some of them who may never get to leave prison, as you have?

TAYLOR: Just like how we started their process from a benchmark mile all the way up to the process of completing the marathon to never give up because I was just right there where they were at and I had life and didn't never think I would get out. But I continue to reach high and put short-term goals to long-term goals processes together and connected the dots.

ABC NEWS LIVE: Markelle, just quickly before you go, we just saw a video of you really sprinting it out. Curious, how fast were you able to run the Boston Marathon?

TAYLOR: The first time was 3:03:00 but last year I ran it at 2:52:00 flat. So, I got smarter in my pacing.