Re: Questions after first day of training in Aikido
What you're experiencing is called "Delayed Onset Muscle Soreness" - (DOMS). Whenever you start exercising after a long time away, your muscles haven't been doing much, and they get sore, usually about 24-36 hours later. The good thing is that it goes away. It might not go away by Monday, but it will go away.
Another good thing is that if you continue training (and stretching) your muscles WILL adapt, you will get stronger, more flexible, and you won't feel all beaten up the day after practice.
If you get into good shape from several months of gradually increased training, you'll find yourself able to do more and more (you may even quit smoking).
If, after getting into shape by doing aikido, you try another activity, such as going for a run, lifting weights, or a different sport/art, you'll find yourself getting the DOMS again, but not for as long, not as severe, and mainly in the muscles that are involved in the new movements.
Welcome to Aikido. Have fun.