Studies show that responses increase if you give a reason for taking a certain action. It doesn't matter whether the reason for buying is a good one or not, as long as you give a reason for people to do so. Of course, it helps — tremendously.
Psychology expert Robert Cialdini notes a study where there was a line at an office where everyone was waiting for the copy machine. The researcher asked to cut ahead. The response was not very good.
However, when the researcher asked to cut ahead “because I have to make a copy” response increased substantially, simply because a reason was given.
Funny, isn't it?
The same thing can be applied to your copywriting. If you give a reason for people to make their purchase now, they will be a lot more likely to do so.