At 31 years old, Chris Anderson was in the prime of his life when he spontaneously lost his vision while teaching a social studies class.

Within hours, a brain scan would help diagnose the middle school teacher with multiple sclerosis, an autoimmune disease that attacks the central nervous system.

He thought it meant certain death.

“You hear those words and it’s unbelievably scary,” said Anderson, now 43, of Shakopee. “I thought, get my bed ready in the nursing home, because that’s where I’ll be. Not true.”

While on long-term disability, Anderson began raising money for the National Multiple Sclerosis Society as a way to pass the time before returning to teaching. The philanthropy would eventually snowball into unpaid, full-time work, positioning him as a powerful advocate. Since his 2004 diagnosis, Anderson has raised upward of $200,000 for the cause — by far the most in the region, charity officials said.

“He gives his whole heart to other people and to finding a cure,” said Emily Byrne, MS Society walk manager. “He dedicates so much of his time to the MS Society and gets nothing in return.”

A gaggle of friends and relatives help Anderson organize a rally, silent auction and team walk each spring. The average “friends and family” team raises about $1,000 a year, Byrne said, but Anderson’s crew averages $16,000 — ranking them in the top 10 fundraisers nationally.

His charitable work has landed him opportunities he’s never dreamed of. Namely, the chance to throw out the ceremonial first pitch at Target Field last season. (Anderson chuckles as he recalls how it landed in the dirt.)

As a lifelong Twins fan, he was determined to sell enough tickets to earn the honor during the team’s annual MS Day, which donates a portion of admission sales to the MS Society. As the second-place ticket seller this year, Anderson gathered his supporters to sing “Take Me Out To The Ballgame” during the seventh inning stretch.

With the aid of a long wooden cane, Anderson slowly made his way across the stadium to belt out baseball’s theme song. His mother, Cathy, two brothers and a few friends stood at his side chiming in.

“You either sit back and say ‘woe is me’ or really turn it on,” said longtime friend Mike Siebenaler, who sang with the group. “He keeps turning on the advocacy.”

Although MS has robbed Anderson of his teaching career and forced him to give up his beloved Harley-Davidson motorcycle, he spends little time sulking about his limitations. People rely on his positive attitude as the Twin Cities’ “MS ambassador,” his mother said.

These days, Anderson struggles to tie his shoes and can’t walk for long periods without resting. But that hasn’t kept him working around the clock to recruit participants for the MS Society’s annual walk — held next week at U.S. Bank Stadium.

“I’m a small piece of something much bigger,” said Anderson, founder of Team Victory. “I tell people that ‘I do this for you.’ ”