It's pretty easy to get anxious and depressed with everything that's happening in the world right now. When you're feeling down, one of the surest ways to pick up your spirits is to go to a park or natural area, listen to the birds singing and breathe in all the nature around you. You can get some of the same effect by downloading birdsong and listening to it on your computer or phone. Unsurprisingly, listening to the sounds or traffic, sirens, lawnmowers and construction equipment has the opposite effect.