The trick to raising smart (and successful) kids is to start developing their thought processes early.

…hundreds of children were tested…

…They could either eat the marshmallow while the researcher left the room, or they could wait until the researcher came back and be rewarded with a second marshmallow…

Children who, in the initial marshmallow experiment, were able to delay gratification and wait to receive the second marshmallow ended up having higher standardized test scores, lower levels of substance abuse, better responses to stress, lower levels of obesity–and so on.

In conclusion, if we hope to raise our kids to be smarter, we should teach them from infancy how to delay gratification.

Source: Want Successful Kids? Science Says Do This | Inc.com