How is everyone exercising?

I have exercise induced asthma. I can walk, even power walk, alright so long as its not cold outside. I do so for about 30-60 minutes almost daily. Basic yoga is also doable. But unfortunately a lot of activities can trigger an asthma attack.

I used to do swimming in college and it helped relieve the asthma symptoms but after moving for work, I am now in a place where the closest ymca is an hour away and the only other pool accessible is the local university that charges $250 a semester (3 hours one day a week thats even open to the public, during times I cannot go)

My doctor says now that I am older, I need to do more than just walking to stay in shape. But what exervise can I even do without wheezing and collapsing? I was hoping to get some advice here