Here’s my Q&A column from the WSJ this week — and if you have any questions for me, you can tweet them to @danariely with the hashtag #askariely, post a comment on my Ask Ariely Facebook page, or email them to AskAriely@wsj.com.

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Dear Dan,

Is it more important to floss or to brush?

—Ting 

It’s a tricky question. In terms of dental health, my understanding is that flossing is much more important than brushing—so if you had to pick one of the two, flossing should be your choice.

But we also need to consider which of these activities people are more likely to do. Here the answer is undoubtedly brushing. So even though flossing does more good for your mouth, brushing is what people are more likely to perform routinely, which makes it more important from a practical perspective.

The underlying issue is why we are so much more likely to brush than to floss. If we thought about our long-term well-being, we would floss regularly, but in dental care as in many other human endeavors, we often don’t act in ways that serve our enlightened self-interest. (We eat too much, save too little and so on.)

So why do we like to brush? In large part because the toothpaste industry has cunningly convinced us that to be socially acceptable, we must be minty fresh. Preoccupied as we are with our social standing, we wake up, feel the mint deficit in our mouths and immediately brush.

In essence, this is a case of “reward substitution.” The basic idea is that some actions just aren’t sufficiently motivating by themselves, so we create rewards for them that aren’t necessarily relevant but still get us to do what we’re supposed to.

Most of us brush not because we want to make sure that we have gleaming, healthy teeth in five, 10 or 30 years; we brush because we feel a socially driven need for that minty feeling right now. Brushing is really a delivery vehicle for mint. That is another reason we don’t floss: By the time we’re done brushing, we’ve got all the mint we need, and the hint of mint on the floss doesn’t add to our minty-ness.

So is flossing or brushing more important? I’d vote for brushing. It isn’t ideal, and we’re not doing it for the right reason, but at least we’re doing it.

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Dear Dan,

How can I make myself wake up earlier? No matter how much I sleep at night, I can’t motivate myself to get out of bed on time. I just lie there and ignore any plans for my morning. Help!

—Diego 

This is another case where reward substitution can play a role, because you need a different incentive that is more motivating. How about promising yourself that if you get up at the right time, you’ll get a cup of fantastic coffee, but if you oversleep, you’ll only allow yourself to have terrible instant coffee—or even prune juice? You could draft your significant other to be the controller so you can’t cheat on your little pledge.

Remember, reward substitution bypasses our natural inclinations (lounging in bed) by getting us to do the right thing (waking up on time) for the wrong reason (for love of fine coffee and/or hatred of prune juice). It’s a handy recipe for better behavior in many areas of life.

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Dear Dan,

My husband and I love each other deeply, but when we get home at night, we usually wind up on our computers until it is time for bed. How can we make ourselves have more romantic evenings?

—Helen 

Try having an eye exam with pupil dilation just before going home. For a few hours, you won’t be able to work or see anything clearly—and you will be forced to focus on your spouse. If this approach works, maybe you can simulate pupil dilation by promising to put on glasses with the wrong prescription as soon as you walk into the house.

See the original article in the Wall Street Journal here.