Good leaders are like good salesmen: Good salesmen are always selling, and good leaders never stop leading. That can be a problem, though; sometimes you need to not lead.
One of those times is when you're on a team that has a leader, and you aren't it. The old military axiom really is good advice: When in charge, take charge, when you're not, don't. As a leader you undoubtedly see things you'd do differently (I know, you're thinking "better") but a team can only have one leader and your best-intended efforts to lead will just be disruptive.
The other time, though, and maybe more important, is when your team is moving itself. They caught your vision, they want to get to the same future state you do, and they see how. And now they're doing it, they're encouraging each other, they're pulling together, they're making it happen. Your job now is to not screw it up.
When you let them run, they energize themselves, they own the results, and they love the work. If you lead overtly at those times, you devalue what they're doing. So monitor, nudge, cheerlead, but stay out of the way. It's those times when you seem like you're not needed that are the proof of your team-building skills.