OK, I have been doing these quite a while, so hope I can help!

First, mid-stream is a bad idea because it can lead to a UTI - obviously for the first few it's good because you know you're doing it right, but once you find the muscles then don't do it on the loo.

Second, don't start off doing them at the bus stop. Sit at home on a comfy sofa with no-one else around (or they'll ask why you're pulling a funny face). Legs close together, not crossed, firmly on the floor. Imagine trying to stop mid-stream and work those muscles, trying not to let your bum clench too (it gets easier!). Don't worry if you do clench and breath in at first, but it's easier if you start of not doing this rather than training yourself out of it. I find I have to be sat firmly on my buttocks to do this, leaning forward gets me no response. You should feel those muscles lift and tighten. Do this 3-5 times and once you're doing it OK, try doing it while watching TV so your face and buttocks are a bit less likely to move too. Do this as often as you need to until you feel you can do this without causing note.

Then try doing it in front of your DH (maybe watching TV or during a meal), giving him no warning. If he asks what you're doing, you're not ready for the bus-stop yet. The more you do, the less you need to concentrate (like learning how to skip or balance on one leg).

Don't worry, doing these exercises 5 times a day for a few weeks will soon give you some response!