Wah. I don't leak wee but something made me click on this thread and now I've realised I've probably been doing all the wrong exercise! 
I haven't had children but just over a year ago I had surgery for bowel cancer. I've had my colon and rectum out, which involved an incision from belly button to just above pubic bone, so right through my stomach muscles. I now have an ileo-anal pouch which is a pouch made from my small bowel, I'm not 100% sure how the muscles work but it relies on pelvic floor more than a normal rectum. The surgery rather weakened my pelvic floor, but I haven't had any leakage possibly because the catheter has done something weird to my bladder.
I have an Aquaflex, but got out of the habit of using it as I've been having nerve pain elsewhere and didn't want to aggravate it. I also find it quite hard to get it into position. I'm pretty sure my um lady bits slope to one side. Is this possible? And is it a problem? It's only since the surgery. I don't think I have a prolapse as I saw a gynae to have my eggs frozen and I think she would've mentioned it if she'd seen one while she was in there. I saw a physio about pelvic floor exercises, she recommended the Aquaflex, but she didn't examine me and I only saw her twice. I was then told by my medical/surgical team to just exercise however I wanted.
So I've been running and also doing the seven minute workout every day including push ups, crunches, star jumps and the plank
I had been meaning to ask my surgeon about the plank etc. as when I do it my tummy bulges downwards, even when I'm sucking my muscles in really hard it has little effect, whereas I can suck them in quite effectively when I'm standing. It sounds like this is actually a sign that the exercises are not appropriate 
Cycling and swimming are not currently options for me, so is walking the only exercise? I don't want to do anything to jeopardise my pelvic floor but my oncologist told me the only thing I could do to reduce my risk of recurrence was to exercise so I'm keen to do something :)
On the subject of pelvic floors in labour, for those who have mentioned it, my Pilates instructor has recently changed the instructions in our class when we tighten our cores, now she says not to pull up on the pelvic floor itself as apparently if your pelvic floor is too tight it can make it difficult to give birth as the muscles don't relax enough to let the baby out. I ignore this as I will never be able to give birth naturally and my pelvic floor needs all the help it can get.
I do my exercises every day. Is it okay to do all three lots of each in one go or am I meant to do them at three different times during the day? I do bonus ones when I'm bored in lectures or whenever I remember 
One last thing, for anyone who finds themselves suddenly desperate to go, when I first had my surgery it often felt like I couldn't hold on and I'd end up rushing to the bathroom, which is what prompted me to see a physio. The absolute best advice she gave to me was to breathe out. It's really hard to force yourself to breathe out at the time as you instinctively hold your breath but breathing out reduces the pressure on your pelvic floor and it honestly does help. It also reduces the panicky feeling.
Sorry for a massive rambly post 