I was taught that when you say InshaAllah, then you are 90%-100% certain that you’re going to do something. You’ll do everything in your ability to make it unless Allah decides otherwise. So if you say that you’re going to show up Insha Allah, then unless you got hit by a meteor you’d better show up.
Funny thing is, when I speak with my non moslem friends over here, it seems that they perceive InshaAllah as “If I feel like it”. So it’s become some kind of a joke, when they’re not sure or reluctant to do something, they add InshaAllah after it. Well guess moslems are partially to blame for it. Some of us might have set a bad example to our non-moslem friends by making lightly of the word.
I hope I can set a better example of how the word is meant to be used, InshaAllah.