Watch: Harbaugh goes tubing with enthusiasm unknown to mankind

Jim Harbaugh has often said he approaches each day with "an enthusiasm unknown to mankind," and judging by a video from the Michigan coach's summer vacation, that doesn't change in the offseason.

The 53-year-old, who fired up his own YouTube account just a week ago, posted great footage on Tuesday of him tubing on a lake with his daughters Addie and Katie.