Does putting money on it actually work?
Of the entries that reached the end of a paid HealthBlocks challenge, 87% hit the goal. People also walk more while one is running: 24.6% more steps a day than the same person takes outside a challenge. Those are our own figures, across 8,774 entries, and the honest reading of them is narrower than the headline.
What the success rate counts
Every entry that reached the end of a paid challenge, and whether it hit the goal. An entry in a challenge that is still running counts neither way, so a live challenge cannot drag the number down while it is in progress, and it cannot flatter it either.
Free challenges are left out. The question is what a stake does, so a challenge without one does not belong in the answer.
The steps themselves go up too
A success rate on its own could just mean the goals are set too low. The step figure is the check on that, and it is measured per person: what someone does inside a challenge against what the same person does outside one.
Each weekday is compared only to the same weekday. Without that, a challenge that happens to cover two weekends would look like an effect when it is only a Saturday.
What this does not prove
It is observational, not a trial. Nobody was assigned to a group. The people in these numbers chose to join a challenge, which means they already intended to move more, and that is exactly the kind of self-selection a controlled study exists to remove.
So this says something about people who commit. It says nothing about someone who never would, and we cannot tell you from this data what would have happened to these same people if they had simply promised themselves the same thing.