Here's a pretty solid reason to keep a positive outlook on life: It might have a pretty drastic effect on your quality of life as you grow older.

So finds a study published in the Canadian Medical Association Journal, and featured by The Washington Post.

The study focused on adults aged over 60 and split them up into three groups: 21 percent who exhibited a high level of enjoyment for life, 56 percent whose enjoyment level was considered medium, and 23 percent who were labeled as low. The more than 3,000 subjects were tracked over a period of eight years to determine whether their mindset had an effect on their physical health.

The results were notable. As the Post notes, "people assessed as enjoying life at a medium or low level were about 80 percent more likely than their happier counterparts to have developed mobility and functional problems." About 4 percent of those who showed a high level of enjoyment developed two or more functional impairments, compared to about 12 percent for those in the middle category and about 17 percent of those who enjoyed life least.

The study provides further evidence of the effects of mental wellness on overall health--giving ample reason for you to think about adjusting your mindset, if you're on the grumpier side.

To that end, check out this Inc. guide to developing a more positive attitude at work. And also remember (hard as it may be sometimes) that your happiness isn't entirely tied up in your work. Take your vacation time, spend time with your family, and recognize that boosting your level of satisfaction with and enjoyment of life will serve you well in the long run.