Every day my sixth-floor walk-up reminds me that I could be in better shape. I hit the gym every morning and do a few endurance events a year, but I’m always out of breath when I reach the top of the stairs.It’s not only humbling, but it’s also annoying. How can I run a 5K at a seven-minute-mile pace and not make it to the top of the stairs without panting?Here’s...
