Why do you want to be rich?

I know why I want to be rich, or at least why I like having more money: Because I believe that I'll be happier as a result.

That belief is what motivates most all human actions, according to Harvard psychologist Daniel Gilbert. Directly or indirectly, just about everything we do -- from waging war to dressing well on a first date -- is motivated by visions of future happiness.

The thing is, as you've probably heard, research has shown that rich folks aren't a whole lot happier than the not-yet-rich. Some wealthy people are generally happy, some aren't, much like the rest of humanity.

But still, whether it's a turquoise Tiffany (NYSE:TIF) box under the Christmas tree or a 5,500-square-foot Toll Brothers (NYSE:TOL) dream house, an awful lot of people with money spend it on lavish items -- only to be craving something else before too long. They don't seem any happier as a result, but the idea that we can buy happiness persists.

Why is that? A new study offers a clue -- one that might have you rethinking how and why you're striving to build wealth.

Can't buy me love
The study in question, by Ryan Howell and Graham Hill of San Francisco State University, suggests that "experiential" purchases actually do increase both present and future happiness. What's an experiential purchase? Simple: One that gives you an experience, complete with happy memories.

It's the memories that are the key, according to Howell. "Purchased experiences provide memory capital," he said. "We don't tend to get bored of happy memories like we do with a material object."

In other words, you'll remember the happy trip to that Disney (NYSE:DIS) theme park long after you've lost the mouse ears, and those memories will continue to provide you with happiness. This is also true of other paid-for experiences, whether it's a watercolor class or a whitewater rafting trip or a day spent tooling around Maui in a rented Ferrari.

But I have fun with the things I buy!
Of course, owning a Ferrari might bring happiness, too. But this study suggests that the happiness would come from the experiences one would have rather than the fact of ownership itself, and I'd agree. I've never owned a Ferrari, but I've known plenty of Ferrari owners and driven quite a few of the cars, and I can tell you that living with a Ferrari is often, to be blunt, a profoundly aggravating experience.

But people (including me) love them, and here's why: For a certain type of car geek, the experience of driving a Ferrari -- especially an older Ferrari -- is like magic. The cars deliver the distilled essence of everything that we car geeks like best -- the sounds and feel and smells and sights -- all at once in huge quantities. It's the best sort of sensory overload and it's fantastic.

It has been almost 10 years since I last drove one, and it makes me happy just thinking about it. And that is what Howell and Hill's research is getting at. It's about the experience, not the thing.

So about that wealth-building thing
Thinking about happiness in these terms can put a very different spin on saving for retirement. Many of us have seen huge holes blown in our retirement nest eggs in recent months, and we've started to wonder if we're going to have enough money to live the way we really want to live -- to be happy -- in retirement.

But think about it. Sure, beach houses and travel and sailboats and clutches for 30-year-old Ferraris can be expensive, but you don't have to spend a fortune to have excellent, happy-making experiences. Back before we had kids, my wife and I got a great deal of joy out of long hikes in the White Mountains of New Hampshire. Those experiences still bring us happy memories; and all for the cost of a few gallons of gas and a roll of film. (And nowadays, you don't even need the film.)

While this might seem like a cup of cheap comfort given the economic situation, with luxury-item purveyors from Nordstrom (NYSE:JWN) to Coach (NYSE:COH) headed for the same hard times that have already hit more mainstream names like Target (NYSE:TGT) and Best Buy (NYSE:BBY), it was just as true in 2005 and 1999 and 1928 as it is now. You don't need a ton of money to live a full and happy life.

The upshot is this: Do the best you can with your retirement portfolio, but don't despair if it isn't as big as you'd hoped. An excellent retirement is still within your reach.

After all, while it might be a cliche, it's now a scientifically proven one: You don't need to be rich to feel rich.

Building wealth to fund a happy retirement takes careful planning and knowledge. The Fool's Rule Your Retirement newsletter will give you all the tools you need, at a price that will leave you smiling. Try it free for 30 days, with no obligation.

Fool contributor John Rosevear, who once set out to buy the Ferrari of his dreams and somehow ended up with an old Aston Martin instead, will now proceed to waste several hours looking at ads for 1970s-vintage Italian exotic cars. He does not own any of the stocks mentioned in this article. Walt Disney and Best Buy are Motley Fool Inside Value picks. Walt Disney, Coach, and Best Buy are Motley Fool Stock Advisor picks. The Fool owns shares of Best Buy. Try any of our Foolish newsletters free for 30 days. The Motley Fool has a disclosure policy.