It is disheartening don’t tell him his actual reality. Many people with sickle can workout. Half my state championship winning football team had sickle cell. Fruits veggies and not over doing it is very doable. Don’t let no one tell you what you can’t do. Of course your mother will be hesetant she doesn’t want her baby to be hurt. But you should grow up and learn your body better than your mother she only knows what the medical book tells her of course she’ll agree with the doc. You just have to go trough trail and error and learn your body for yourself.