New to this and have just had a senior moment and set my goal to ADD weight! Doh! How can I reset it?

I did the same thing myself. There is no way of changing your goal other than messing with Wii settings or cheating with your weight to make the machine think you beat your goal.

One way of doing it is picking up something thats heavier than yourself to reach your goal during the body test. Then youll be able to set a new one. Another way is what I did myself. Go to the Wii menu, change the time a few weeks ahead (would have to be months if you set it to do months), go back on Wii fit, do the body test and itll tell you its been a while and the time is out, would you like to set a new goal or something like that.

Bit annoying though that you have to go through all that because you made a mistake. I hope they will fix that in their next game... if they do one of course At least there are ways of doing it without losing all your hard work and unlocked advanced modes. I would HATE to delete my data after all that!

The Wii asks me about once a week if I want to change my goal. So you just have to wait till it asks you if you want to change your goal.