The thing is not to feel guilty. We all set out to do things in the hope that it will just make life a little simpler a little less stress free. Doing these happiness projects, room a month, decluttering projects should NOT be adding stress to our lives. If it is adding stress reconsider if it is something we need to be doing right now. We put so much pressure on ourselves now a days to fit everything in and blame ourselves when we can't do it all.
Jess you were saying you spent a lot of time playing with the kids on the WII and not reading your book. So what. That is what made you happy at that time. It was only afterwards that you said, I just wasted time on the WII when I should have been baking, reading etc.
Anyway I think one of my happiness goals is to stop putting pressure on my self. I will do the important things and try not to worry about the small stuff.