It's one of the ultimate ironies of life--when you're young, you're often dying for time to pass so you can get older or summer vacation can finally arrive; when you're older, time seems to fly, and you'd give nearly anything for the hours you so carelessly rushed through as a child.

Your clock may tell you that time passes at a constant speed, but both subjective reality and psychology prove that's nonsense. Turns out that time feels slower when you're learning and experiencing new things, hence that sense of sluggish hours experienced by kids, who are new to everything. Once your life is full of routine and busyness (a period where you could really use a 25th hour), it becomes harder to reclaim that feeling of long days.

Who Has Time for Wonder and Discovery?

One option is to try to stay childlike, to keep learning and experiencing new things. That's great when you can manage it, but when it's 3 p.m. on a Wednesday, and you have to finish that report before picking up one kid at soccer and the other at the school play and then find something to feed everyone, taking time out to wonder and discover may not seem like a really practical option.

Handily, though, science has found another way to slow down your experience of time, one that just about everyone can squeeze into his or her schedule and that doesn't require finding space in your life for big projects such as finally taking up the cello or investigating your latent passion for photography (though by all means, do those types of things when you can). The blog of startup iDoneThis recently included the technique in a roundup of ways to feel as if you have more time.

Less Couch Potato, More Good Samaritan

What's the basic idea? Doing things for others actually makes your days seem longer. It may sound totally counterintuitive that after many hours of work and family responsibilities, you shouldn't just kick back on the couch with your favorite TV program, but according to the Wharton School's Cassie Mogilner, who is cited in the post, if you really want to get a sense of time expanding, the right course of action is to spend more of your limited downtime on others.

"Mogilner and her colleagues asked some people to spend 10 or 30 minutes 'doing something for yourself that you weren't already planning to do today.' Others were assigned the task of spending 10 or 30 minutes on someone else, doing something that hadn't been planned," iDoneThis explains. How did the two groups compare? "Spending time on others expanded people's sense of the future."

The takeaway here is that simply swapping out a self-serving leisure activity for something focused on others will expand your sense of time. "Decompressing in front of the television or getting a massage might be fun and relaxing, but activities like these are unlikely to increase feelings of self-efficacy. Indeed, people's choice to spend additional leisure time on themselves may partly explain why the increase in leisure time in modern life has not increased people's feelings of time affluence," Mogilner explains.

Little substitutions can make a big difference, according to the research. "Carve out 10 to 15 minutes a day to do something for someone else," Mogilner urges.