Back in 1905, a 55-year-old Johns Hopkins University medical professor named William Osler gave a retirement speech, in which he opined that the "effective, moving, vitalizing work of the world is done between the ages of 25 and 40 -- those 15 golden years." By contrast, Osler argued, those over the age of 40 didn't have anything new to offer, and he thought it would be best if people stopped working at age 60, since by then their brains were pretty much shot.
Osler's belief that brainpower, creativity and innovation had a limited shelf life sounds a bit daft today, but up until recently, scientists actually did believe that brain cells died off without being replaced and that after our youthful peak, our mental capabilities steadily declined with every passing year. Today, however, we know that many people don't experience a noticeable drop-off in brainpower as they age, and that some mental abilities that depend upon accumulated knowledge and experience actually tend to get better over time.
Research shows that regular mental workouts -- such as the sort that you get from taking a college class, reading a challenging book or studying a foreign language -- actually improve the function of parts of the brain associated with memory, learning and decision-making [source: Cohen] But again, the resolutions that stand the most chance of success are focused and modest. So this year, set a reasonable goal of acquiring some new knowledge. It's easier now than ever, now that educational consortiums such as Udacity and Coursera are offering massive open online courses (MOOCs), which actually allow you to participate in free classes taught by professors at elite universities like Columbia, Brown and Stanford [source: Blankenhorn]. Of course, a college in your hometown is also sure to offer a short night-time course on something of interest.