An Ex-BYU baseball player wrote a great article on positivity for lifehack link:
"15 Differences Between Positive People And Negative People
As you know, it is a drastically different experience being around positive people versus negative ones. If you are striving to be more positive yourself, here are 15 ways you can do so..."
He's a great guy, his name's Justin Sua. He also a great and popular daily podcast called "Increase your impact." It's only 3-5 minutes long and I love it... I listen to it every day.