When Bryony turned thirty, she was sad to still be in a sales job she’d never liked. She decided it was time to stop procrastinating and find a new career. For David, New Year’s Eve had him looking in the mirror vowing this would be the year he lost weight. And for James, it was watching another month pass without his angry outbursts decreasing. Next month, he promised himself, he would try harder.

If you’ve ever vowed to change at the start of a new month, new year, or a major birthday, you’re not alone. Researchers even have a name for…