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,

I know that you’ve often written about money as a motivator. This semester, I would like to join a yoga class that requires a substantial one-time registration fee. Will paying this amount in advance motivate me to attend regularly to make up for the money I’ve spent?

—Jeff 

Yes, we’re much more likely to do things when we commit to them in advance and have sunk costs. One challenge with this approach is that, over time, you might forget that you have paid that large initial fee. I would recommend that you print the receipt from your one-time registration fee, laminate it and attach it to the door of your refrigerator. This would not only be a constant reminder to attend your yoga class but also might be useful encouragement to eat more healthily.

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Dear Dan,

I am very concerned about climate change, and I try to minimize my own consumption. I don’t drive much, avoid products packaged in plastic, grow as much of my own food as I can and use video chats with my relatives instead of flying to visit them. At the same time, I know that my individual choices and sacrifices are not having much of an impact on this gigantic problem, so I find it hard sometimes to keep to these restrictions. How can I increase my motivation and stick to my principles?

—SF 

Climate change is certainly one of the toughest behavioral issues, for exactly the reason you cite: Our individual actions feel like a drop in the bucket, and this discourages us from acting.

One of the best ways to boost your motivation is to use the people around you. You could, for example, rally some friends, neighbors, co-workers and family members to join you in your effort to limit consumption. You might start by asking them to commit to one action, such as putting a five-minute cap on showers, and then all of you could track your success together. By acting together, you will feel that your impact is larger.

One example of such motivation comes from a study recently conducted for the grass-roots political group Postcards4VA by the social psychologist Brett Major, described in the journal Behavioral Scientist. The study looked at what motivates people to volunteer more for political action. As you might expect, those who had joined political groups were more likely than the unaffiliated to act politically. Group participants were also more likely to have a positive experience and to intend taking future action; they were also less likely to get burned out. So before you give up on your cause, call a few friends.

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Dear Dan,

I live abroad. My girlfriend has never been to my hometown, and my parents are always asking me to bring her when I go to visit them. In October I plan to do that, though my family doesn’t know. What would make them happier: to surprise them when she shows up with me or to tell them in advance and let them enjoy the anticipation?

—Miquel 

Surprise and anticipation can each lead to happiness. In your case, surprising your parents might make the first hour of your visit more exciting for them—but after that, it might take a few weeks for them to get over the shock. In this case, I would advise you to give them plenty of time to look forward to your joint visit.

See the original article in the Wall Street Journal here.