I remember a stubborn Russell insisting he had to paint the outside of his house a few years back... Trying to operate a snow blower is in the same category of not accepting your limitations.
Challenging yourself should be attempting small activities several times a day AND learning to adapt to your limitations.
It is very difficult for those of us that need to rely on others for help, but being a caregiver is often a thankless and difficult role as well. What is obvious to you, is maybe not obvious to them. The best way to handle these situations is to explain to your current and future caregivers what you consider top priority for them to help you with--as well as activities you might sometimes be able to manage, but when you're in a flare, that you'll need help with.
I had a friend that was very intuitive about when I needed help and she often noticed when my pain was starting to escalate before I did. I highly suspect this was because her mom was very ill and in severe pain most of her childhood. --That is not the norm and I'm glad that while my son is considerate, he never developed that particular skill set, which I think is an unfair burden.
Most people will either try to do everything for you or will wait to be asked for help. Frankly, many of us get annoyed when our loved ones try and take over all our responsibilities without asking...
Your daughter's bf is grown, so trying to be subtle or guilt him into doing something is just not a good idea IMO. It is EASIER to hire a stranger to help out because it's expected that you will tell them what you need. If that's not an option, than I would suggest next time you say something like, "I really appreciate that you're working on the floors. I know I said that was my first priority, but would you mind going and clearing the driveway now please?"
So while I can understand your frustrations, I think you have a responsibility to clearly express your needs.