The government has now relaxed its ‘once a day’ exercise rules for everyone.
The NAS explains here https://www.autism.org.uk/get-involved/media-centre/news/2020-04-09-guidance-on-exercise-coronavirus
Government guidance is here:hps://www.gov.uk/government/puications/coronavirus-outbreak-faqs-what-you-can-and-cant-do/coronavirus-outbreak-faqs-what-you-can-and-cant-do#can-i-exercise-more-than-once-a-day-if-i-need-to-due-to-a-significant-health-condition