I have read every post on this PMR forum (I read all there were before I joined and have read every one since) and I don't remember anything that I would have called a "regimen" - if I had I would have registered it because one of the things you have to do is be careful.
Contributors have said they are still able to run or cycle miles a week, others say they work out in the gym - and this time last year I barely managed the 200 yds into the village using crutches! Strangely, most people who are able to continue exercise are male - and it is acknowledged that men and women experience PMR very differently.
When you have PMR whatever it is that causes it seems to prevent the muscles responding normally to the demands of exercise - it seems to result in muscles tiring very quickly when asked to do sustained or repetitive actions. I couldn't hold a phone to my ear, for example, without my biceps developing cramp. Suddenly I couldn't use the cross trainer at the gym without developing claudication in my thighs after about 2 minutes instead of being able to manage a good 10-15 mins. I had no power in my legs to do steps, it seemed awfully hard work and left me exhausted. I still skied - but at the beginning of the season I could do only a couple of short runs - and would still have sore muscles the next day. I live at the bottom of our mountain so I went every few days and by the end of the season I could ski for a couple of hours no bother - but longer runs were still difficult without a rest. The break on the lift between short runs was enough.
Anyway - you aren't going to be going skiing so I'll shut up about that - but physiotherapists who know about PMR all warn about trying to do too much because of the extended recovery period and risk of leaving muscles damaged. The DVD from the northeast of England PMR and GCA support group (developed by MrsK amongst others) has a bit on it by a physio if I remember rightly. What is important is to keep the muscles doing something to avoid muscle wasting due to pred - it sometimes happens but not always.
Walking is felt to be as good as anything else for that purpose for the legs - and it also protects against osteoporosis. Half an hour a day is recommended, "briskly" officially but that is relative! My brisk in the early stages of PMR was definitely not my normal "brisk"! The best way to go about it is to choose a short walk close to home - do it and see how you feel after it. Then increase it by a few mins each time - but beware: I have found myself at the top of a ski run thinking "I feel really good, I'll do one more and go home" only to feel as if I've hit a brick wall halfway down and had to crawl to the nearest seat. MrsO on here had a similar experience on a walk near her home - and had to sit on a neighbour's wall to summon up the energy to get home! Start with a flat walk that is easy to abort and get home - not a circular walk round a lake! I don't know about you - but I found uneven ground next to impossible, it is still difficult and is certainly far more tiring. Also, doing 3 lots of 10 mins achieves exactly the same as one session of 30 mins - that applies to any form of exercise - and means you won't get stranded somewhere.
I did aqua aerobics at the level I could manage - I didn't feel I had to compete with the others (who were mainly over 50 too) but the pool had to be warm. Another lady with CFS (chronic fatigue syndrome) was in the class and often left half way through but also said that as time went on she realised she could do more and more. It covered everything - we used woggles/noodles and foam dumbbells to do resistance training of arms and shoulders. Our local B*********** was excellent at the time - off-peak membership for about £30 a month and an aqua class every day. I did it pre-pred and it kept me mobile - once I had done it I was no longer anywhere like as stiff. I also managed Pilates with adaptations and Iyengar yoga - but you must have a good instructor.
A couple of 500ml water bottles with water in (not necessarily full to start with) are a good and cheap way of making adjustable weight dumbbells for out of the water and do a few bicep curls, rest and repeat. Whatever you do in the gym or out of it NEVER do long series of repeats, never do repeats to exhaustion or to pain (no one should do exercise until it hurts, no pain no gain is rubbish and no good instructor should say it). One lady got herself one of the pedal sets - like cycle pedals - and used that at home sitting in a chair watching TV and found it helped.
Now you are on an effective dose of pred it is all too easy to think you are now well - you aren't I'm afraid, it doesn't work like that! Do everything in small doses - whether it is housework or exercise, even eating a biscuit crumb by crumb will demolish it eventually! Keep your protein intake up and carbs down - and that will help avoid muscle damage too, keeping the supply of protein building blocks up has been shown to help and avoiding carbs does help avoid the midriff bulge that pred is so prone to causing.
Hope some of this helps - the trick though is to make sure you go out regularly because it is all too easy to sit at home and mope but a walk in the fresh air makes a lot of difference to how you feel. Not that the UK weather recently has really been particularly encouraging has it ;-)