My friend recommended The Science of Happiness. In this podcast they have a "guinea pig" (usually a really interesting person) and have them try a happiness activity from The Greater Good Science Center. They introduce the activity and discuss the person's experience. In the second half of the podcast, they go behind the science of why each particular activity makes someone happy.
Happier with Gretchen Rubin is a little less science based, but is still fantastic. Gretchen and her sister give weekly happiness tips (I love these!) and discuss different aspects of happiness and hurdles throughout their lives. They also focus on creating good habits.
What's your favorite happiness-themed podcast? (Or, what podcasts make you happy?)