An alternative to making things fun is to make things unconscious and/or automatic. No healthy individual complains about insulin production because their pancreas does it for them unconsciously, but diabetic patients must actively intervene with unpleasant, routine injections. One option would be to make the injections less unpleasant (make the process fun and/or less painful), but a better option would be to bring them in line with non-diabetic people and make the process unconscious and automatic again.