With all the turkey, eggnog, and chocolate, it can be hard to stay healthy during the holidays. Investing in a smartwatch before the holiday season kicks into full gear can help you stay on track with your health goals, and right now, one of the best is available at an all-time low. The GPS-equipped, 41mm Apple Watch Series 9 is down to $349 ($50 off) in a variety of colors, including the new pink, at Amazon and Walmart as part of their early Black Friday sales. The 45mm configuration is…