With a hot-link, you just have to un-check the box (you'll see the picture in your post immediately, even before you "post" your reply.
If the picture is on your computer and you put it in your post, the work around is to make the post, like Marvin did, open the picture and right click on it to copy the image address. Go back and edit your post__leaving the original picture in there__and treat it like a hot link as described above.
Ninety-nine percent (99%) of the pictures I post are "online" already, so it's easy to hot link them to threads/posts, but there are a bunch of free hosting services available (but if they ever go offline, of your account expires, then the links are broken and no more pictures (like some of my posts from a decade ago).