I really began to notice the difference undergarments could make immediately after my c-section. I had read that wearing a girdle after childbirth could help a woman's stretched out muscles go back to normal more quickly and I had a couple ready to wear when I came home from the hospital. And boy, did I need it. I was pretty beat up. Due to a shift change and a new nurse who didn't want to "wake the doctor" I pushed for five hours with no progress at all before my emergency c-section (those five hours are not something I would wish on anyone). My body was not happy.After we got home I tried on the girdle I had bought and saw an immediate, dramatic difference. I felt like my stitched up muscles were supported and I could actually make it up and down the stairs (slowly).
Over the next few months I got used to the support of the girdle and I started to notice an improvement in my posture when I was wearing it. It makes me more conscious of how I'm sitting or standing. Lately I'm paired it with the corset that I wore under my wedding dress, for a more seamless look. It isn't a heavy duty corset (I wouldn't want to deal with wearing something tight, or uncomfortable), it's just the kind that hooks up the back and it adds to the improved posture. I like that I don't have to worry about bra straps slipping and it stays in place because it's a larger garment.
And now I finally have a full slip that fits (I do also have a large fluffy half slip that I wore under my wedding dress, but it's not exactly practical for everyday wear).
Getting dressed has become quite a process, but when I don't have supportive undergarments on under a dress I feel kind of naked! Even when I wear pants around the house without the girdle or corset I feel rather exposed and under dressed.
The best part about finding undergarments that work well is that I don't have to worry about panty lines showing through or dresses that are too sheer without a slip (and some dresses made of surprisingly thick material can become semi see-through in the sun) because I'm already covered. It doesn't guarantee that every dress will pass my own personal modesty test (some just can't be helped) but it certainly helps!