After I had my braces removed, I was given the traditional retainers (metal band), & told to wear it round the clock for 6 months (except for eating & brushing teeth). After that 6 month period, I just had to wear them at night. After a couple of years of wearing them, I stopped. But then a couple of yrs ago, I noticed that 1 of my front bottom teeth was being pushed back, so I went back on the retainer (Invisalign), which I'm still on right now, to correct the tooth.
Wearing a retainer gives you a sense of freedom, that you can now eat whatever you want, but still have to follow "doctor's orders". There is no pain at all, except for getting the retainer initially fitted, & also being tightened when its needed. You do speak funny, a cross between a lisp & a British accent. They aren't annoying at all, except for keeping them clean & them slipping off every once in a while.
Overall, its a great experience.