1. It’s not a 'sprint' if you don’t stop running.
It’s simple: Employees can't be effective if they are never able to let up on the gas -- they will inevitably burn out. There needs to be slower periods to ensure success in the long run. Take time to celebrate successes between sprints, even if as a leader, the successes aren’t exactly what you would want them to be. Success for a startup CEO may mean exiting but for employees that simply represents future risk. You have to celebrate the things important to the team. You need to celebrate building the product, selling it, updating it and awards for it.