This post is by staff writer Sarah Gilbert.

I was cleaning the kitchen and listening to NPR (my default state) when A.J. Jacobs came on, discussing the various diets he’d committed to for Drop Dead Healthy, his latest stunt journalism book — this guy practically invented the genre. Naturally, most of the diets were a bust, but he did conclude that exercise was always a smart way to keep slim. “I literally run errands! So, I’ll run to the drugstore, buy toothpaste and then run home,” he told Scott Simon.

I shouted at him, something like, “You stole my line!” But he couldn’t hear me.

I, too, run my errands. With three young children at home and a husband in the military — he’s been away more than he’s been home in the past three years — I have to combine everything. So I run to the bank and I run to the bookstore and I run to buy coffee beans and I run to drop off film at the photo lab. Whenever my parents drop by or a friend tells me he’ll watch the boys for a bit, or now that my oldest is responsible enough to watch his brothers for 25 or 30 minutes while I run somewhere, I’m off, putting as many different to-dos into one small bit of time. I’d just be proud of myself for saving time and multi-tasking, but as I’ve learned, it saves money, too.

It’s a restriction I impose on myself
Running somewhere with a specific need in mind — take Sunday, when I ran to get cash and coffee beans — really limits my extraneous shopping. Cash fits in any pocket and I can carry one small-but-bulky item in my running vest pocket. So when I happened to stop by the bookstore to check out the 30% off local presses sale they were having, I found a great deal on a book I want. But run 1.75 miles with a book and a bag of coffee beans? Awkward and I couldn’t really afford it. I left the book on the shelf.

I’m one of those people who needs a lot of reminders not to overspend, and because I know I’m like that, I appreciate the self-imposed restrictions.

You can get this restriction a number of ways, of course — many of our readers carry only cash that they have budgeted for the shopping trip, day, or spending category. But I particularly like the run-your-errands strategy, because it includes some side benefits that may also lower my expenses too (now and in the future): I don’t have to pay for a gym, and we all know that exercise can decrease potential future health issues.

Avoiding associated spending
Another thing running my errands does for me is keeps me from what I call “associated spending.” You probably know what this is even if I made up the term: for me, it’s stopping when I’m out for a cappuccino or a quick lunch. I do it often when I’m with one of my children, especially if we’re bundling errands together. We’re in the bookstore, and there’s the coffee shop next door! We’re hungry already and we didn’t bring snacks. Oh, and let’s buy a little toy because it’s so adorable and I really don’t want to get in this argument right now. Mom! Did you realize the grocery store is only two blocks away from the used game store?

If I’m running and hurrying back to my kids — either because I don’t want to leave the oldest in charge for all that long, or because my friends and family only have so much patience — there’s no way I’ll stop for a cappuccino or give in to the now-nonexistent wheedling.

If you’re not up for running your errands, you could achieve this by setting yourself a time limit or going on your lunch break, when you have to be back at a specific time and won’t be able to dawdle.

The blessing of paying for child care
With my husband away, I have to pay if I want to leave the house at night. (I’ve learned after too many very bad choices made by my well-meaning relatives that free babysitting is never free. I’ll be paying in counseling and nighttime terrors for that R-rated movie Aunt E. let my kid watch for years.) I’ve figured it out down to the minute: for most of my fantastic and well-worth-it babysitters, it’s $1 for every five minutes.

This means my nights out on the town are few and far between. I go to a writer’s group once a week, and bring chocolate ($5) and very occasionally a bottle of wine ($8-10). As my babysitting is so expensive and I don’t like to leave my kids too frequently, I rarely go out for dinner or drinks with friends — maybe once a month or less. While I’d of course love to have the going out experience more often, the practicality is too dear and I see this as a blessing: it’s so easy to spend $50 or more without thinking much of it at a nice restaurant or wine bar. Instead, I meet friends with kids at parks or coffee shops or at each others’ houses, where it’s a lot harder to realize that you’ve ordered $30 in drinks and you still have to leave a tip.

For couples, this can represent itself as enjoying “nights in” rather than going out for date nights; putting the kids to bed early if they’re young, or letting them stay up late watching a (parent-approved!) movie if they’re older, and having alone time in another part of the house without having to leave a tip. There’s something about that psychological jolt of having to hand a teenager $40 or $50 that can help keep us from swiping the credit card at at brew pub.

Restrict yourself it’s freeing!
While my methods may not work for everyone (and lots of you probably don’t have kids which impose their owns sorts of limits), if you need some psychological barriers to spending, there are plenty of ways you can join in the fun. And when I say “family,” below, I mean childless couples and empty nesters, too! Here are a few:

  • Ride a bike or take the bus, or use the smallest family vehicle, for errands. I have a cargo bike that can load so this wouldn’t work much for me. But if you can’t carry a lot home, you’ll buy less. It’s a pretty simple and elegant restriction. Try it next time you go to IKEA!
  • Commit to only going out to restaurants in your local entertainment book. The “Chinook Book” is a local entertainment-style book that is in several Western U.S. cities now; and I feel confident the restaurants with coupons in the book are good choices. But keeping myself to those restaurants (and those with coupons I haven’t used) would be a great way to limit my spending.
  • Make a family “in” night tradition. We have an absolutely sacred Friday Family Movie (and Pizza) Night. My kids have been asking for other traditions, too, like game night. As long as you’re not ordering expensive to-go food (we only order pizza once a month or so, making it from scratch or doing the frozen Trader Joe’s variety other weeks), it’s a great way to be together and to enjoy yourselves without contributing to the family credit card balance.
  • Set family goals. If you have kids, they may not get excited about financial goals — or maybe they will — but either way, you can exploit it for savings. Maybe you’ll work to identify two dozen bird varieties in your local parks (you’d be amazed at how easy that is!). Maybe you’ll try to run a 5k together, and spend your free time training. Maybe you can learn a language together (enough to go on a family vacation with all the money you save). Maybe you just want to save up enough for a big birthday party. Creating a family goal is a good way to share your restrictions and have something to fill your time in a positive way so you won’t spend money.

Do you need restrictions like these to save money, or are you a spending Jedi able to control yourself with no effort at all? Have you tried any of the tips above or others I haven’t mentioned?