After the most fun-filled, relaxing holiday that I've had in a long, long time, today I find myself in a funk. Part let down, part my-house-is-trashed-and-I-don't-feel-like-cleaning-it, December 26th is always a transition day for me. It's time to put the holiday mindset behind me and get back to real life, and once I do, I feel better. But for some, that transition can be difficult, especially when moving forward means heading into some of the darkest, coldest months of the year.

Post-holiday depression isn't uncommon, and it can be avoided by focusing on your healthy lifestyle habits. Eating a balanced diet, avoiding alcohol, exercising, and talking about your feelings are all things that can help you stay on track, according to Healthday.

If you do find yourself feeling blue, not taking an interest in your usual activities, sleeping too much or too little, gaining or losing weight, feeling "foggy" or not being able to concentrate and symptoms persist, then you may want to address these common signs of depression.