Agreed.
I was diagnosed with asthma back when I was little - I'm also a dancer who has often had to do full-day rehearsals.
After getting over a really bad flu with the help of a naturopath back in Yr 9, I fixed up my diet and have rarely had to use my Ventolin since. Often I'll notice I'm slightly more out of puff than other people, but it's not too bad and so long as I have decent rest periods and drink water, it's cool
Since getting my Ventolin, I think I've only ever had to use it once for a minor "almost" asthma attack. Anyone who's suffered from asthma will know when their asthma is acting up - all they have to do then is to use their puffer, and all is good
When their diet gets better and they become stronger/more fit, they will actually rely LESS on their puffer. Swimming is widely documented as being the best activity for this, however basically anything else will work as well - just take it easy to start with, keep an eye on your body, and take your puffer with you