After weeks of sipping eggnog and relaxing with family, the holidays are finally over and it's back to your normal routine. Yet, rather than stepping into high gear, you may find yourself feeling less than energized. Could it be all that holiday turkey still weighing you down, unwinding from family time or is it post-holiday fatigue?

"After any big event -- a vacation, a wedding or the holidays -- there can be a lull after," says New York-based clinical psychologist, Linda Smith. Here, she shares her tips on fighting post-holiday fatigue: 

Plan something to look forward to. Part of what's to blame for the post-holiday slump is that we spend a month or more gearing up for the holiday season and in a week's time, it's over. 

Without anything glittery on the horizon, getting back to the daily grind, especially in the darker days of winter, may cause seasonal depression to sink in. 

To alleviate these blues, walk into the office armed with a plan for a vacation, a party or even a self-challenge. This will give your brain something positive to focus on and can help overcome depression and post-holiday lethargy. 

Create an action plan. Set a business goal such as a new marketing strategy or a sales target and lay out an action plan before returning to the office. 

"Having a good plan can help you get back into the swing of business as usual," says Smith. 

Related: 7 Ways to Get Excited for 2014

A new challenge provides the brain with something to focus on, giving you a boost of energy and preventing sluggishness from setting in. 

Organize your desk. Nothing can make you feel more overwhelmed than staring at a mountain of paperwork upon returning to the office. While it's best to organize your desk before leaving for a holiday, take a couple of hours in the New Year to clear off your desk before settling in. Starting with a clean slate can help your mind focus on the tasks you have planned.

Meditate. Taking a timeout to simply listen to your breath go in and out can re-energize you. 

"Yoga discovered [that breath impacts energy] before psychologists," says Smith. 

If you find yourself feeling depleted of energy, take a five-minute break to inhale and exhale deeply or take a walk outdoors. Many studies have shown breathing in fresh outdoor air can help relax the nervous system and re-energize the brain, improving focus and creativity.

Related: Stressed Out? Relax With These 5 Free Apps

Make a to-do list. Before stepping back into the office, craft a to-do list to help focus your mind. That said, Smith warns to avoid making a list the night before returning to the office, as it can then be difficult to turn off your brain and go to sleep. 

"A lack of sleep will affect how you feel and perform the next day," she says.

The list provides a clear idea of what lies ahead, helping you to avoid becoming overwhelmed upon stepping into the office in January.

Frame a new picture. Adorn your office with a new photo of your family or a trip you took during the holidays. The positive thoughts you will have when looking at the picture will help boost your energy levels. 

"Mood and energy have a strong relationship," says Smith. While a positive mood increases energy, a negative mood depletes energy, explaining why we're grumpy when we're tired. 

"Recalling a nice memory when looking at a photo may lead to more positive thoughts such as, 'I am loved' which in turn relaxes muscles and breathing [and even] leads to a change in behavior, [causing you to smile more often]," says Smith.