Ok gang! I'm trying to keep this as simple as possible. What do you think of points system? I don't want to make it overly complicated - remember someone is going to have to keep track of everything

Going by Robbie's suggestion each 10 points earned will equal 1 entry to the prize raffle.
Weight loss (per week)
Maintaining goal weight (+/- 2lbs) = 2 points
Biggest Loser for the week (by percentage) = 3 points
Exercise
Completing a weekly workout challenge ie. 15 pushups every day for the week = 1 point/day
1 hour of exercise = 1 point
Healthy eating
Drinking 8 glasses of water a day = 1 point/day
Trying a new healthy food or recipe for the week = 1 point/week
Taking a multivitamin daily = 1 point/day
Eating five servings of fruits and veggies daily = 1 point/day
Eating two servings of dairy a daily = 1 point/day
One time points
3 points for every percentage of starting weight you lose (eg lose 5% of starting weight; get 15 points at end of contest)
Reaching your goal weight = 10 points
Achieving a race PB = 10 points