This comes up so often; people are looking for help in making them feel better emotionally, and I've made numerous replies talking about neuroscience and mood, and suggested some books to read, so I thought I'd do a more general post. Full disclosure; I'm not a psychiatrist, psychologist or neuroscientist and I don't play any of those on tv. I am someone who's suffered from depression, negative thinking, anxiety ... and I'm also a librarian, so one of my coping strategies is reading about things, and I've come across increasing numbers of books about "the neuroscience of happiness".
There has been a lot of research in the last 8-10 years on brain chemistry, brain plasticity, meditation, exercise and mood ... and how they all fit together. A lot of books have come out which are geared toward the lay person. One book that gave me some hints was "Younger next year for women" by Chris Crowley and Dr. Harry Lodge, an internist working in gerontology. It talks about how exercise can cause chemical changes at the cellular level, and actually slow aging, both physically and mentally. That lead me to start looking for other books.
You can go to any public library online catalogue; New York, Toronto :), and look up subject headings like "neuropsychology", "exercise-psychological effects". Most library systems will use the same standardized subject names. You'll come up with a number of suggested titles, which you can A) order through your public library, B) order from Amazon, or C) download a pdf in some cases if you google the title.
There have been a proliferation of titles in just the last 2-3 years. Here are just a few books to read about the new discoveries in neuroscience;
"Spark: the revolutionary new science of exercise and the brain" by John Ratey (psychiatrist), which talks about how the physiology of exercise affects brain chemistry. This will make you want to get up at 6:00 a.m and go running every day.
"Blue mind" by Walter Nichols who's apparently a marine biologist and this is about how proximity to water is beneficial. I can't recommend this yet, because I haven't read it yet; I'm going to order it from the library, but it looks interesting.
"Hardwiring happiness" by Rick Hanson. Also haven't read this one, but it sounds really promising in terms of using principles of neuroscience to re-program negative thinking.
"How god changes your brain" by Andrew Newberg (a neuroscientist). It is unfortunately named, because it isn't actually about god; more about how meditation can change neural pathways; those "well-trodden paths" of negative thinking.
"The brain that changes itself" by Norman Doidge (neuroscientist). Talks about how the brain is more plastic and open to change than we thought.
ETA; I'm in no way advocating not going to a doctor/therapist or not using anti-depressants! Go to your doctor/therapist and I myself have found anti-depressants to be effective.
And here; have a happy video