The most relaxing thing I can think of doing is watching a cheap old PBS show called 'The Joy of Painting'. I've been a big fan for at least 15 years, when I first started watching it on the local PBS channel piped in from Detroit. It features Bob Ross, who did the show for years before he died. The man could do a fantastic painting in less than 30 minutes.
Even if I didn't find him completely relaxing, I'd still find it interesting just to watch the guy work. A blank canvas to a beautiful landscape in under 30 minutes with nothing but his imagination to guide him. Holy malolloy. But the best thing is that he's showing you exactly how to do it yourself. I know that when I get older, I'm going to sit and learn to paint in his method. He's very convincing that anyone can do it.
Millions of people around the world have watched Bob Ross paint on PBS or other TV stations. The guy is quite popular and there are many art schools done in his style, trained in his methodology. I personally think he was a genius. If nothing else, he's one of my favourite people. If I had the chance, he and Trudeau would be two people I would go back in time to meet.
The pic below (which amused me) came from here.