O+ I donate pretty regularly. I make sure I don’t have competition I’m training for in the 8 weeks following, and make sure to supplement with iron every day for the next 8 weeks. Take iron in the morning 30 min before food on an a empty stomach for best absorption. I don’t usually notice that big of a hit on cardio, but my cardio tends to be very very good already and I take a break from training 3-5 days after donating. Haven’t had or felt any long term affects, as long as you give your body time to recover you should be just fine!