Cold weather and dark skies can make just about everyone feel lethargic at times. The feelings known as "winter blues," are more than just your imagination. It's a real condition called "Seasonal Defective Disorder," or SAD, and you may feel depressed, without energy, or simply not yourself. Fight off the winter blues with these tips and keep yourself going strong, all winter long.

Stay Hydrated. You may not feel as thirsty as you do in the summer, but you need to remember to stay hydrated. Drink plenty of water, of course, but if you need to warm up and want something tasty, consider a cup or two of hot green tea. Green tea is rich in anti-oxidants, which gets your blood moving and improves your energy level.

Eat Small Meals Throughout the Day. Maintaining a healthy blood sugar level is crucial to maintaining your get-up-and-go. Instead of three large meals, switch to six small meals throughout the day and evening. Select foods that are rich in protein and complex carbohydrates.

Exercise at Least 30 Minutes a Day. Staying moving is good for you on so many levels. Exercising will release endorphins, natural pain-killers and mood boosters. If thirty minutes sounds like a lot to you, break it down into 10 minute increments. Even small changes like taking the stairs can help you maintain a healthy balance, both physically and mentally.

Light Therapy. Experts agree that one of the primary ways you can fight the winter emotional doldrums is to be exposed to light. If natural light isn't possible, then consider investing in light therapy products, which mimic the sun's rays and are thought to alleviate symptoms of depression.