I think the suggestions about vitamin D and being in the company of others are good suggestions, and listening to uplifting music too. (greensmoothiegirl.com)
And they always have uplifting music playing in the background that I can't help but hum to while shopping. (texturesofgrace.com)
The show plays uplifting music as we see workers sauteing vibrantly colored vegetables in gleaming kitchen. (thelunchtray.com)