The gym is a good place, and for the sake of your health and your fitness—and your deep, abiding need to do something other than sit for hours on end until death's sweet embrace envelops you in its arms—you should go to it on occasion. Sometimes, though, "on occasion" is just not in the cards. Maybe you're short on time, or it's snowing sideways, or you haven't done laundry in a week and know full well that wearing the same gym clothes twice is, for you, a non-starter. Friend, it is time for you to invest in a set of adjustable dumbbells.

Buying free weights is always a frustrating endeavor because they tend to be wildly expensive proportionate to how pricey you think cumbersome chunks of iron outfitted with rudimentary handles should cost. Weights also take up a good amount of floorspace, making the task of accumulating a full set in your tiny apartment a difficult one. (Also, your lease probably doesn't allow it, and your landlord would be highly displeased if they were to find out that you are storing hundreds of pounds of metal in a tightly-concentrated space on the sagging hardwood floors they should have replaced a decade ago.)

Adjustable dumbbells help mitigate these problems, at least a little bit! Instead of having a fixed amount of weight at either end of the handle, adjustable dumbbells use mini-plates that allow you to adjust the amount of work involved in lifting it. Mine use a lever that slides over the top of the plates, securing the plates underneath with a plastic clasp. Others adjust the weight using pins—much like machines at the gym—or even dials that can be merrily turned like a middle-school combination lock to select your resistance level of choice.

The most common variety of sets goes up to 50 pounds per side, and although I know that you can lift more than that—I know—it should still be enough to accommodate a solid 90 percent of your needs. Time for biceps curls? Boom, you instantly have a pair of 30-pound dumbbells. Front raise? Slide them down to 20. Use the full 50 pounds per side for a squat or a dumbbell deadlift. You can even do a chest press while supine on the floor—or, in the alternative, adjustable dumbbells make a great pair elevated push-up handles, which ensures that you get that full bench press-style range of motion.

*All of these weight amounts for each exercise are arbitrary and not actually the ones I use, unless they impress you, in which case, yes, this description of my workout regimen is accurate.

The novelty of adjustable dumbbells, unfortunately, does not mean that they are less expensive than their traditional free weight counterparts—heavier sets, especially ones from big-name fitness brands, go for around $300. But that's much less than you'd spend on a rack of free weights, and not a whole lot if you think of it as a modest tack-on to your monthly gym dues. Honestly, you might even find that owning a set allows you to skip paying for a membership altogether. Do be sure to get a rubber mat to protect your floor, though. Dumbbell imprints of any size on your hardwood are not a good look.

Watch Now:The Rock Picks His Next Great RoleJay Willis is a staff writer at GQ covering news, law, and politics. Previously, he was an associate at law firms in Washington, D.C. and Seattle, where his practice focused on consumer financial services and environmental cleanup litigation. He studied social welfare at Berkeley and graduated from Harvard Law School... Read more