It doesn’t take 21 days to wire in a habit, says psychologist BJ Fogg. Sometimes, all you need is a shot of positive feeling and emotion, a dose of celebration. Celebrating is a great way to reinforce small changes — and pave the way for big successes.

Neuroscientist Robert Sapolsky shows us the surprising ways that our brains get mixed up between the physical and metaphorical — and how this can pit us against each other.