Too often we thank the people who have really mattered in our lives only in eulogies or with sympathy cards sent to their relatives. The delayed gratitude not only deprives the dearly departed of a special moment, it also means we've missed an opportunity to feel truly happy ourselves.

There's a better way, suggests Amherst College Prof. Catherine Sanderson, who was in Minneapolis Sunday to lecture on "Positive psychology: The science of happiness" as part of One Day University — an event sponsored by the Star Tribune.

Rather than waiting to say thanks until after the fact, Sanderson said, write a "gratitude letter" to someone who has changed your life for the better. Then take the letter with you on a visit to that person, reading it out loud when you meet. Imagine the power that type of face-to-face thank you can carry — for the person being thanked and for you.

It's a simple suggestion — one of several Sanderson offered up Sunday, along with fascinating accounts of the research that backs up their effectiveness. (Another happiness tip: Try smiling more — as broadly as possible — even if you don't feel like it. For more on Sanderson and her strategies, go to http://tinyurl.com/nqrwfro.)

With any luck, we can all name multiple people who deserve our gratitude. A schoolteacher, a former boss — maybe a high school coach who taught life skills you still depend on today.

Maybe you haven't talked to the teacher, boss or coach since you left school or the workplace. It doesn't matter. Just write the letter before it's too late. And then, if possible, make the trip that Sanderson recommends — even if you have to spend a little money. As she points out, spending on positive experiences — not stuff — is another key to happiness.