I have to say, I am surprised of the benefits I'm already getting after such a short time. For a start, all the problems with my arms and knees are almost gone, or at least I'm not aware of them anymore. New small physical problems spring up every week and later disappear, as they are likely caused by practicing movements and postures that until now have been alien to my body. Incidentally, I even discovered the existence of a few muscles I didn't know were there at all. The encouraging experience I want to share, is the speed at which this "shape improvement" happens. Keep in mind that even if I am not particularly old or overweight, I still started after about a whole decade of life with an office job and zero interest in physical exercises.
Let me assure you that during the first two or three weeks I was truly exhausted after each training session, with my legs feeling weak and hurting for days. But the aftermath clearly felt better and better each time. The turning point came about after three weeks: suddenly for the first time during a training I wasn't looking at the clock and thinking "Oh no, we still have X minutes before I can rest" but instead I was caught by surprise by the final whistle and thought "Oh no, we've already finished today"!
There are still times of course, when an especially hard session takes the toll on me. After we finished the beginner's course and joined the regular class, the first "real" training was so demanding, that I couldn't keep straight while walking or use the stairs without feeling severe pain in my upper legs for three-four days. But the great thing is that the fitness improvement process is addictive, the more I do it the more I want to do it, to the point that now I wish I could train every single day.
There are a few ideas that I believe helped me a lot in the process of getting my body used to a regular physical activity, and especially to heal and become always ready for the next training. So here are some suggestions, based on what I've been doing myself in the effort of getting used to our training weekly routine.
1) Stretching, the ultimate key to shrugging off the pain and stiffness of the day after! It just works wonder, if there is one and only thing you should really do at home between trainings, it is this. And no matter how little you do, it's always useful, even half a minute here and there is going to give you some relief. Make sure you know what and how to stretch: target the muscles that actually need it at the moment, find out what position allows to stretch those muscles specifically (you can also discover these yourself), and remember that you need to pull reasonably: pull hard enough that you "feel" it but not so hard that it hurts. Your awareness is the key to understanding if a stretching exercise is targeting the muscle you really want!
2) Tackle the exercises you hate the most at the training by doing them again at home. No, this is not some kind of masochism or a spartan attitude, it is a very down-to-the-ground tactic: we hate those exercises that are particularly hard for us personally, but by doing them again at home, regularly but at our own chosen pace, we simply get better at them and they become progressively less hard to do, until hopefully we won't hate them anymore when we have to do them in a class. A lot of people hate push-ups for example, and when you're really out of shape even doing 10 of them in a row can be demanding... So how about keeping in mind that every now and then you can drop to your livingroom floor and do a bunch of push-ups? At home, nobody is telling you how many you should do, so do as many as you can before hating it, and then add a couple more to push slightly beyond your comfort zone. This comfort zone of yours grows larger in time, and the amount required at the class feels progressively less and less uncomfortable. The point here is that instead of waiting for this to happen just by practicing push-ups when you have to (at the class), which means to keep hating them for a long time ahead, you can speed it up if you keep the idea in mind of doing some homeworks which, if spread around during the day, won't really annoy you at all.
3) Endure your presence at the class. Do not skip trainings because you're tired or aching (unless there is an actual, real injury of course). Especially in the early weeks, it was common to see people missing sessions, which I normally presumed was because the previous training had been quite harsh for us beginners. But I forced myself not to skip any training because of these reasons, not even a few times when I was actually sick or feverish, and I can testify I felt better as soon as the training started. I still went back to feeling pretty badly after it ended... but the thought that I made it through the training despite the circumstances has been a boon for self-esteem each time. Be honest with yourself however, and do not do this if you have a real injury! If the training makes it feel worse, that means you really need to rest, but if the training makes you forget about it, then you're good to go!