We are unable to do these as they require a level of assessment that we are unable to offer. Often these require GPs to state that there is no reason why someone can’t do an activity (eg a marathon) but this requires the GP to take an unacceptable level of risk, and often to say this definitively, you will need to have further investigations, such as a scan of your heart or an exercise stress test, which the NHS won’t send you for in these circumstances so you are advised to seek a private opinion from a suitably qualified specialist.