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Yoga is very good for breathing. I used to teach people to ride, and often they stopped breathing as they were clinging on as though it would help. Breathing exercises can help a lot with anxiety, for controlling the associated over-breathing. I found it very helpful for thinking about the 'inside' and allowing all the external things to melt away. My yoga teacher at the time was in his 80s.
I've done yoga for about 6 years. The really good thing about it is that it is a place where you feel safe because no-one makes judgments about the others in the class and we are all encouraged to do everything to our own limit as it is 'our practice'. Quite a few people are overweight and quite a few come on their own without a companion.
Breathing slowly is fantastic for anxiety, especially if you can develop a slow, full in-breath followed by an out-breath that is twice as long. Try to do it for 15 minutes when you are relaxing and at any time of the day when you can think about it. It's good for when you are feeling stressed as it slows down your heart beat. If you Google slow breathing you'll find that it also reduces blood pressure if done regularly over a period of time.