Riding his bike around his old neighborhood in Denver, Joe Carabello found himself alarmed at the number of homeless people, especially those living in parks right next to empty baseball fields.

So Carabello, a successful real estate developer, came up with an idea one late-summer day in 2010: a weekly softball game for the homeless.

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"I thought it was such an odd idea, and to be honest with you, I didn't think the chances of the program succeeding like it has were very good," he said. "How do you gather people from every walk of life, different ethnicities, ages and genders and on top of that, they live in an unstructured world?"

Using his unique calling card - a softball marked with the time and date: 9 p.m., Tuesday - he still hits the street, reaching out to missions and organizations in hopes of recruiting enough players for a weekly game.

Back then, he had no idea whether anyone would actually show up but slowly word started to spread to places like the parking garage where Rose Henderson lives alone after losing her job six months ago.

Now, every Tuesday, she joins dozens of players on Carabello's field.

[It's] like you're a part of a team and part of society again," she said. "I just come here for the game and to have a good time. … I'm not trying to escape the situation I'm in, I'm just trying to make it the best that I can."

Ricky Gessick, a former Marine wounded in Iraq, said playing softball provided him a break from the stress and struggle of the street. He said the game turned him into a new person.

"I turn into, just you know, 'Super Rick,' I guess," he said. "I put 125 percent in, no matter what. … I just clear my mind and think baseball. Everything else - all the homelessness, the soup lines, all the waiting, all that crap - that stays out there. … That's why I love that."

ABC News' Clayton Sandell contributed to this story.