Next time you're buying food, multiply the cost of it by 365. That's the "lifestyle cost" of eating that kind of food every day.

So, having a $15 lunch every day costs $5,475 per year.

For once-per-week costs, you can multiply by 52. So, $70 drinking every Friday night has an annual cost of $3,640.

Why is this useful to do? First, you'll realize that many things that seem cheap, aren't. You might very well be spending $7,000 per year on coffee, if you're at cafes a lot. That might be a fine expense, but it's worth knowing.

Much more importantly, you'll realize that some things that seem expensive, also aren't. If you're spending $7,000 per year on coffee and you're a very heavy internet user, you might consider scaling your cafe-habits back slightly and buying the highest end laptop possible. A lot of people will get a cheaper laptop to save a few hundred dollars, but spend thousands per year in consumption that they don't really enjoy all that much.

Likewise, the cost of having a massage once a week is probably lower than the cost of a night of drinking at a nice bar. But for many people, drinking seems like no big deal, but getting a massage seems like luxury.

Try it out. For a daily cost, multiply by 365. Weekly, multiple by 52. Do this regularly and you'll get a lot more bang for your buck.