Ever notice how someone’s sunny disposition (or, conversely, their sour, dismal outlook on life) rubs off on your own mood? As it turns out, high spirits are infectious. For teens especially, spending time with friends who tend to be more cheerful can be a boon to mental health. According to new research, happy friends may cut a teen’s chances of developing depression in the next 12 months by 50 percent while doubling the likelihood of recovering from depression within the same time frame. If you know any teens who struggle with depression, encourage them to get involved in extracurricular activities or join a volunteer organization where they are more likely to meet energetic, joyful people. And don’t forget: Your own mood will likely have an impact on them (and others) as well! What are some ways you try to stay in a good mood? Sound off in the comments!