All the pictures of Blue doesnt have a harness. He jumps them naturally, infact if there there and he has run of the place he often jumos them when were sitting on the sofa not asking him to.
Honey does it naturally too but I haven't any recent of her as she isn't jumping at the momment.
If they didn't like the harness I wouldn't put it on them but they both love it and don't mind, I have some weho don't like it so they don't go on one.
It wholely depends on the rabbit, mine have been use to them from when they are young which I find is easier