Mine was finding the right diet.
I am one of those people who knew I was gaining every year but I couldn't seem to do anything about it.
Unfortunately, I really like my food so many diets never lasted longer than two days.

But as of today, I'm on my THIRD day

and feel really content with the way it's going. In case anyone's interested it's the CSIRO total wellbeing diet. CSIRO is the Commonwealth Scientific and Industrial Research Organisation, Australia's national science agency.
I also have to say, good on you, NurseMichelle, for holding a 'biggest loser' at work. That's a great idea!