Have you ever been a member of a health club?  For many years in the past, we were members at the Y.  It was great because I could go for a walk on their indoor walking track in the worst of weather.  Our son took indoor swimming lessons and again, even if it was snowing outside, he could still have his lessons.   They had good exercise classes which I took advantage of several times.

A lot of areas have several health clubs.  For example, if someone lived in Richmond, Virginia, the richmond health club would be available.  So if someone gives the excuse that the weather is bad or their allergies bother them when they go for a run outside, suggest a health club where they could exercise in a nice, safe, climate-controlled environment.