Reed, who played for Gwynn at San Diego State, threw away seven cans of smokeless tobacco from his locker, and another two from his car, before Saturday night's game against the San Francisco Giants, according to MLB.com.
"It's one of those things where I've done it for so long it's just become a habit, a really bad habit," Reed said Saturday. "It was something I always told myself I would quit, like next month, and the next thing you know it's been six or seven years."
Gwynn, who played for the San Diego Padres during his 20-year career, died on Monday after battling cancer. He was 54.
Gwynn was diagnosed with cancer of a salivary gland in 2010, and publicly stated he believed it was caused by his smokeless tobacco use throughout his career.
Reed said he first tried smokeless tobacco in his junior year of high school.
"It started to get bad my first year in pro ball and it's one of those things where I've always done it," Reed said. "I'd come to the field and throw one in and have multiple ones. I'd have one on the ride home, one on the way to the field and it was one of those things where I always had one with me."
Information from The Associated Press was used in this report.