A posture fix for CHEAP

I've been trying to have better posture, but it's really hard. I was thinking about buying one of those back sling things to help improve posture, but I'm too cheap to buy one. And then my classmate Michael (he's a professional dancer) told us this awesome [CHEAP] trick.

Put on a kinda tight tank top over whatever you're going to wear, then take the front and lift it over the back of your head so the tank becomes like a shoulder holster. Then wear it around the house.

I only started doing it yesterday and I can tell there's been a huge improvement!
I have lots of back problems. The muscles in my back are not well trained to good posture anymore.
I had an accident when I was seventeen, and I fractured multiple vertebrae in my back and since then I have had lots back issues, then after two pregnancies...well, my back hates me, we'll put it that way. The muscles are constantly tired. I don't just have bad posture, I shlump like no one's business, especially when I'm at home or alone. Then on Sundays when I try to sit up for church my back is just screaming because it's not used to good posture anymore and those muscles are lazy now.
I've gone to physical therapists, and they help a lot! But doing the exercises at home...with kids...well, it's really hard to get motivation to do. It's so much easier when I have a physical therapist (personal trainer really) with a timer telling me what to do, and I just have to do it. Buuut, I don't have one anymore. Anyhoo, so I can tell you from lots of experience that this little trick is helpful. :)

I noticed that when I'm not wearing the tank (keep in mind I've only been using it for one day, and a morning) that subconsciously I stand up straighter, like I would with the tank on. Also, it helps do a little of the work of keeping my back straight because it's pulling around my shoulders. Basically it's taking a little weight off my muscles so they have an easier time getting whipped back into shape. I took off the 'tank shoulder holster' and sat on the bed at my computer and my back started aching so much I put the tank back on, and it was much easier to sit straight up. Of course it's not a miracle maker, I have to put work into it and consciously be straitening my back all day. But it's a huge, cheap!, help.

I just thought I'd share since most of us (especially if we sit at the computer much) are getting horrible posture which not only looks bad, but it can even lead to internal problems, and create headaches, and all sorts of nasty stuff.
So, try it out!
Tell me what you think? Is it helpful to you? Not that much? Have you tried something else that works better or just as good?

~Crystal