CHICAGO (CBS) — A retired Chicago doctor and diehard Cubs pounded the pavement Sunday to raise awareness for patient and caregiver safety.

As the Cubs prepared to take on the White Sox, Dr. Dave Mayer began his trek at 8 a.m. at Guaranteed Rate Field, and arrived at Wrigley Field about three hours later. The ballparks are about eight miles apart.

Mayer is walking across the U.S., visiting all 30 Major League Baseball stadiums. Since February, he has walked almost 200 straight days, more than 1,300 miles, and just under 3 million steps.

He said he is having fun, but his cause is serious.

“People don’t realize that behind cancer and heart disease, more people die from preventable errors, and we’ve got to figure out how to improve that, for the safety of those at the front lines as well as the safety of our patients,” Mayer said.

Mayer hopes to complete his tour by the start of Spring Training in 2021.

As for Sunday, he said he wished he could walk to a seat at Wrigley Field and watch the Cubs play ball. But of course, the COVID-19 pandemic means the teams are playing with no fans in the stadiums.