Saddest day of the year? 5 ways to boost your mood on 'Blue Monday'

Mondays in January can be rough, with their typically less-than-ideal weather, post-Christmas bills to pay, and a lack of motivation at the beginning of the week. And, according to one formula, these factors make Jan. 18 the saddest day of the year, aka "Blue Monday."

Before you crawl into a corner, know that Blue Monday has its share of skeptics. It was first observed in 2005 when a psychologist "calculated" the most depressing day of the year using a mathematical formula as part of an advertising campaign for a travel company, according to Snopes.com. That psychologist, Dr. Cliff Arnall of the United Kingdom, has since become the face of the #StopBlueMonday initiative, which promotes travel to the Canary Islands.

The real "saddest day of the year" has yet to be scientifically calculated, according to Snopes, because our feelings are more complicated than a simple formula. What's more, critics have said that using a formula to calculate mood misrepresents the best ways to treat clinical depression, which should be done with the help of a health care professional.

If you're feeling particularly down-in-the-dumps today, however, there are things you can do to improve your mood. Try beating Blue Monday (or Blue Tuesday, or Blue Wednesday) with these five activities:

Help those in need

People who do things for those in need are more likely to be happy over time, studies have shown. And the health benefits don't stop there. People who volunteer regularly (about one to two hours a week) have been shown to live longer and are able to take care of themselves in their old age, according to the Corporation for National and Community Service.

Get up and move around

Many types of exercise have been linked with a lower level of depression, according to the National Institutes of Health. While experts are sure of the relationship, they are still studying the potential causes, such as the release of endorphins, the transmittal of serotonin and the distraction from worry that exercise provides.

No matter the cause, experts suggest finding a physical activity that you enjoy is the best way to reap the benefits of exercise because you'll be more likely to keep up a routine.

Go outside and stare at trees

Even five minutes outdoors staring at trees can improve your mood, according to the New York Department of Environmental Conservation. If you can't make it to a park, researchers have even found that looking at pictures of nature can have similar, though less powerful, effects.

"Numerous studies show that both exercising in forests and simply sitting looking at the trees reduce blood pressure as well as the stress-related hormones cortisol and adrenaline," the DEC's websites reads. "Using the Profile of Mood States test, researchers found that forest bathing trips significantly decreased the scores for anxiety, depression, anger, confusion and fatigue."

Say thank you

Listing out the things you are thankful for can help improve your mood, one study found. People who journaled about their mood did not see the increase in positive feelings of those who wrote about why they are grateful. In addition to the happiness boost, those in the "grateful" journaling group also found that acknowledging their gratitude made them feel even more thankful.

Cuddle with a pet

Especially if you feel lonely, adopting a pet (or even just visiting an animal) can improve your happiness level. Just 30 minutes with a furry friend can help, according to the non-profit Pets Are Wonderful Support.

"Enhanced hormone levels of dopamine and endorphins, associated with happiness and well-being and decreased, levels of cortisol, a stress hormone, following a quiet 30-minute session of interacting with a dog," the organization wrote.

If you or someone you know is experiencing signs of depression seek medical help.