Fisting is a goal of mine
I have experimented on myself. I can get all fingers and thumb into my asshole, but I can't get my knuckles in. Yes, my hand is lubricated. I wonder whether a partner would have better success in entering me. I also can spread open my asshole. I would like to be fisted by myself or by a partner. I will tell you if I feel pain.
I can't fist myself, simply because I can't twist my body around enough. I have been fisted a few times by others, and loved it. Lots of lube is the answer. On occasion I've asked them to get out, but I meant it to be only a brief respite, before going in again.
I have tried it again. The problem is my arm must be in an awkward position, and my arm won't move any more. Two of you have responded have somebody else shove his/her hand up my ass. That makes sense, but the hand must be well lubricated. Would any of you offer to do that for me?