There are a few options out there for a GOOD sports bra. They are PRICEY, but worth it.
I have big girls, that are old and long and floppy!
The best favor you can do yourself, if you are large breasted, is to do some serious real life and online shopping and find a bra that is comfy and supportive! This will require, lots of trying on and ordering and returning! I know, it sucks, but finding a great bra, is so worth it in the end!
I just found a great underwire, front hook, racer back bra at Kohls.com. It's a Vanity Fair!
Looks cute in front, supportive, has a wide back, and wide, soft comfy straps! I don't even feel like I"m wearing it! And it comes in several colors!
Does not pinch, bind, ride up, down, slip, slide, dig in a leave grooves in my shoulders, and so on. I work out in this bra, I work in it, live in it, I love it! I have 2, waiting for the next online sale, gonna order a couple more in other colors.
If you are wearing the proper size bra, it runs true to size.
You don't have to have a sports bra to workout in, you just need a good, supportive, comfy one that serves the purpose you've purchased it for, what ever that may be.
For thinkfit, if you need to wear 2 from Wal Mart, I would really suggest you explore some other options. WM sports bras bite. Cheap, you get what you pay for. And wear 2? I have purchased a couple from WM. I still have them, I wear them on weekends at home, while my good ones are in the wash. Since I am large breasted, WM's sports bras, waller my girls around until I have one big ole cyclops boob in the middle of my chest, that's just wearing one! If I put on 2, I'd have some strange mountain peak in the middle of my chest. I'm glad it works for you, it's just not for all of us. It actually tickles me to think how I would look.
And for the record, those pull over bra's are the spawn of the devil, not to bad to put on, but, I'm sure it would be easier to get out of a straight jacket when you want to get it off!