He became a star left-handed quarterback at President Theodore Roosevelt High School, winning the Interscholastic League of Honolulu's Back of the Year award in 1962.

[3] A speedy runner, Lum was converted to an outfielder in the Braves' organization after having played first base in high school.

On May 22, 1969, with the Braves leading the Mets 12-0 in the 7th inning, Mike pitch-hit for Hank Aaron who was 2 for 3 with a home run, single and a walk.

After two more seasons as a fourth outfielder and back-up first baseman, Lum was acquired by the defending World Series Champion Cincinnati Reds for Darrel Chaney on December 12, 1975.

He logged just one at-bat in the 1976 National League Championship Series with the Philadelphia Phillies, flying out in game three to end the seventh inning.

[9] Aware that Lum was to become a free agent at the end of the season, the Seibu Lions offered him a three-year deal worth one million dollars.

He signed with the Chicago Cubs shortly afterwards; on August 12, he clubbed a two-run home run off Terry Leach of the New York Mets for the 100th pinch hit of his career.

On May 22, 1969, Lum cracked a two RBI double off the New York Mets' Al Jackson pinch hitting for Hank Aaron.

Following the passing of White Sox hitting coach Charley Lau that March, Lum assisted his replacement, Joe Nossek over the rest of the season.

He was fired at the end of the season despite the fact that the Chisox won eleven more games, drove in 55 more runs, and had a higher batting average (.253, vs .247 in 1984).

When the Hawaii Winter League resumed play in 2006 after eight inactive seasons, Lum joined the North Shore Honu.