Love Japan Collection:

The Daruma doll, also known as a Dharma doll, is a hollow, round, Japanese doll modeled after Bodhidharma, the founder of the Zen sect of Buddhism. These dolls, though typically red and depicting a bearded man (Dharma), vary greatly in color and design depending on region and artist. Though considered an omocha, meaning toy, Daruma has a design that is rich in symbolism and is regarded more as a talisman of good luck to the Japanese. Daruma dolls are seen as a symbol of perseverance and good luck, making them a popular gift of encouragement.

The eyes of Daruma are often blank when sold. Monte A. Greer, author of Daruma Eyes, described the "oversized symmetrical round blank white eyes" as a means to keep track of goals or big tasks and motivate them to work to the finish. The recipient of the doll fills in one eye upon setting the goal, then the other upon fulfilling it. In this way, every time they see the one-eyed Daruma, they recall the goal. One explanation how this custom started says that in order to motivate Daruma-san to grant your wish, you promise to give him full sight once the goal is accomplished.

So, install first only one Daruma's eye and reach your goal. Then, install the other eye to remind your accomplishment. :)

VIA WIKIPEDIA