We got into fisting a little differently than most couples, I’d bet, but it's both of ours favorite part of sex now (with maybe the exception of 69). We started fisting by accident, actually. We always had a really great and active sex life, but I never actually liked being fingered. I think it reminded me of those awkward boys I dated earlier in life who would paw at my pussy and never got me to cum. On our third date, my now husband went down on me and have me the most mind-blowing cunnilingus I'd ever had in my life, BEFORE I did anything to him, so I knew he was a keeper and I also didn't see any reason to do fingering (and I'd never heard of fisting!!!).
Then, after being married for about four years, we had our first c***d and my vagina tore pretty badly during the birth. It hurt like hell, but after the doctor sewed me back up I was as tight as ever and so when we were getting ready for the birth of our second c***d, I started reading about stretching exercises for my vagina. We did those for the last two months before our second c***d was born, and to help me relax, I used a vibrator on my clitoris while my husband massaged my vagina. We did not try putting the whole fist in at that time (basically he put three fingers in my vagina and pulled it down to stretch the muscles), and after our second c***d was born, without any tearing this time, we stopped and didn't think anything more about it (but it had really made me hot; I was horny as hell throughout both pregnancies). About nine months after the baby was born, however, I was feeling really horny and so I asked my husband one night, kind of shyly, if he'd be willing to finger me again like when I was pregnant, and of course he happily agreed. After trying it a few times, we decided to see if we could actually get his fist inside me. It took several months of practice, as I would always get nervous right at the end and tighten up my muscles so his whole hand didn't slip in (although he always pointed out that I was freezing at the widest point and that I'd be better off letting it go over the top, so to speak). I always played with my vibrator when he was doing it, and I always had incredible orgasms, so it was a lot of fun and sexy as hell. Then one night, right before I was about to cum, I started coughing and my body naturally relaxed and his whole fist just popped inside me and I nearly exploded out of my skin with the orgasm that followed. After that, I started working really hard on relaxing and started taking the whole fist pretty quickly, although I would still freak out when it was time to pull it out (now it almost makes me cum a second time). Now we can go from start to having the whole fist in me in under five minutes if I want, although we usually take longer and make a night of it. I also love to see him masturbate while he's fisting me, so he does that, and then after I cum, he keeps the hand in me and then finishes off on my belly (or, if I'm really loosened up, he'll rotate around and cum on my face, although that's less comfortable for him because of the angle and can sometimes hurt me, too).
A few things to note:
We do NOT fist like most of the couples in the movies that we post. He is much more gentle and would never try to punch fist me or some of the things in the videos. That's fine with me, as I love the feeling of being full more than being stretched (although I'm starting to like the stretching, too).
He always uses gloves when fisting, because they smooth out his hands and nails and are more slippery, and we use a thick gel lubricant that doesn't run off to keep things very slippery. We use A LOT of lube (like a couple bottles a week, which makes us feel silly at the pharmacy) and so we put down a towel under me to keep the bed/floor clean. It's our code when we're out in public with friends; he or I will ask "do we have any clean towels" or something like that. I like it because I can see his pants get tighter when he knows what's coming when we get home!
We started watching fisting movies to see if we could learn any ideas. What we learned is that we're not interested in that kind of fisting ourselves, but that they are fun to watch together and so we've built a big collection.
We probably fist 2-3 times per week. More than two days in a row and I get pretty sore, although two days in a row is my favorite.
I still feel VERY tight in my vagina and my husband swears there is no difference at all when he makes love with his cock (which is very nice but not abnormally large). In my husband’s own words, “If I pull my fist out and slip in my penis, she is still as tight as the day we met right even after fisting. As long as you take time to warm it up, use lots of lube, and make her comfortable, the vagina relaxes on its own and doesn't get stretched out.”