If there’s a “Lean In” gene, I like to think my mom has it.

She postponed a career to have four boys in less than four years, and then returned to night school to get her degree in education while some of us were still in diapers. I can remember her lugging me to College Park one evening so I could pretend to be a drowning swimmer for an oral presentation she was giving on lifesaving.

Over and over, she made me practice flailing my arms and cry “Glug, glug, glug!” on cue, intent on ensuring a realistic demonstration. My performance had its desired effect: The class laughed; she got an “A.”

Sometime after my sister was born, mom went on to teach at an elementary school in one of the poorest neighborhoods in Baltimore, reasoning that’s where she was needed most. It was a tough place. Many students lacked basic necessities, and local roughnecks would occasionally wander onto campus to stir up trouble.

My mom, a small woman, was hardly a match for the oversize teens but — true story — in the midst of one confrontation, a ruffian mistook her attempt to break up a fight for a kung fu move, and she never seemed to have problems after that.

Mom eventually left teaching to snag a position closer to home in a tiny library branch at our local shopping center, no mean feat given its equally tiny staffing needs. About this time, she announced that she wanted to start getting back in shape. We were skeptical, especially after she tried running around the neighborhood high school track and could barely finish a lap.

But she kept at it, adding lap after lap, until one day she was running marathons up and down the East Coast. She soon took to triathlons, and began racking up a number of wins in her age group.

I once asked her, after I had started my own family, how she ever did it? How did she raise five kids, hold down a full-time job and still have the energy to train at such a high level?

She gave me a puzzled look. She said it was all a whirl. She just did it.