Giving Blood, What To Expect After?


I have decided to give blood for the first time in my life. I've read that you can't do much physical activity after and you may feel drowsy the same day as well. I am a pretty active person, guessing I won't be able to go to the gym for a few days after? anything else to expect?

also, is there any long term affects to donating blood? I couldn't find anything online, I plan to start donating at least 3-4 times a year