I’ve noticed it all summer long—small minute observations of not being on my game. Whether it’s slowing down in the ring as the rounds add up or the feeling that I’m going to run out of breath when I walk from home to my writing room or from my office at work towards the subway.

These are things I take for granted: having the pep and vigor to work hard through my 16 rounds of training at Gleason’s or walking at my fast pace wherever I go, in fact hating when I amble as some sort of flaw in the process of how I move through space

And yep, it’s been hot and humid, even at 6:15 in the morning. And as for Gleason’s – well it’s a boxing gym! Air conditioning is for the winter when cold air barrels through because there’s very little heat—and summer, well, the heat and mugginess is just part of the “allure,” not to mention a sure fired way to loosen up tight muscles.

In contemplating why my stamina is off, and why there have been times this summer when I’ve had to stop in the middle of running pads with my trainer Lennox Blackmoore, sit for a while under one of the overhead fans with a wet towel on my head before picking it up again on the double-end bag or the speed bag, I’ve wondered if it’s just the heat, or something else.

Is it turning 64? Is it the process of the body inevitably slowing down even when one does the same thing repetitively? Is it mental? A sense of not being in the moment, my thoughts wandering off somewhere, stealing glances at CNN’s early morning news show as I shadow box around the ring—feeling my guts tighten and cringe at whatever the latest outrage is about children being separated from their parents or yet more cuts to things like food stamps and healthcare?

In thinking about stamina—that ability to work at something long and hard whether it’s something physical or mental or both for that matter—I’ve been thinking through the processes that gives one the feeling of invincibility as one works through the problem, whether it’s running five miles in a set amount of time, boxing a set number of rounds, or putting in the hours to write a book; efforts that require focus, attention, and a sense of being present with what one is trying to accomplish.

I’m hoping that my being “off” in the gym—is some combination of heat and mental focus, and in thinking it through even further I do have to own up to the fact that I’ve not been resting as I should and have been letting the day-to-day stuff we all live with “get” to me.

And so in trying to tease out stamina—I can see it as a “trifecta” of sorts: one part being in shape, one part being focused, and one part being present enough to let it all happen. And sure, it can be physical too—but the truth is, I just don’t buy, at least not yet, and so off I’ll go on Monday to work it out on the bag again.