Also, telling a depressed person their answer is to exercise is like telling a homeless person that they just need to get a job. The not having a home prevents the getting a job. If they had the ability to find a job, they wouldn’t be homeless (except obviously the people who don’t make enough from their job to support themselves, but that’s a whole different issue that shouldn’t exist).
So even if someone does have the time, getting the depression under control may be necessary before the exercise seems like a reasonable possibility.