You can work out while on OMAD just make sure to monitor how you feel and your calorie intake, you don't want to risk hurting yourself. Also, when you do eat, make sure to drink plenty of coconut water so you recover all your electrolytes and nutrients. Watching the weather is another impotant factor, if you exercise when it's too hot (anything over 80) you can run the risk of losing too many nutrients and needing to break your fast to drink something with electrolytes or eat a snack. While you could feasibly ignore this and continue to fast, you then run the risk of passing out (I know this from the experience of playing collegiate sports).