I would say starting Youtube. When i first started I was a fundamentalist christian (Think a 'nice Westboro Baptist Church'). I would say 'Hate the sin, not the sinner'.. and 'You're going to hell for being a homosexual, but I don't want you there'. Through debates, videos, and learning.. I changed my opinions on many many things - not just that.
Recently, it's actually made me try to find ways to be more energetic which starts with a healthier lifestyle and habits, it benefits my videos as well as myself. So far the only thing I've changed is my sleeping patterns and that's helped tremendously alone. It's not much, but baby steps xD
i made a EU referendum reaction video. i did not pull any punches. i asked people to leave their views and thoughts in the comments but asked if they could refrain from arguing. and amazingingly everyone was really cool about the whole thing