Don't bring up the game mechanics in play until absolutely required.
There's no need to announce it's a skill challenge, how hard it is, or how many successes or failures are required. That's meta. It breaks flow.
Instead, stay in the flow. Give the players enough background to know what problem faces their characters, and what some of the options might be.
DM: You have followed the road through the grasslands into a hilly jungle. There the road ends, probably consumed by centuries of aggressive forest. The way is dangerous, for dark things dwell here, but also because the terrain is difficult. Looming in the distance are some big mountains.
DM: What do you?
Now you have their attention. They know what the problem is. They're thinking about solutions.
Player: I want to see if I can pick up the trail of the old road through the jungle.
Player: I have keen eyesight. I'm just scouring the ground for stone markers and such.
Now you interact with the system, because you know specifically what is required.
DM: Make a Perception check. DC 18.
Player: 19! Thierra scouts ahead, finding bits of stone rubble here and there. It's slow-going, but we can follow the road for a bit.
Sometimes you need to tug the players back to the fiction.
Player: Can I make a History check?
DM: I dunno. What is Thierry doing?
Notice, the DM doesn't have to argue or be confrontational. Gently nudge the player back into character.
Player: Um... I want to think back to my geography class at the Arcane College. Do I remember any maps that showed how the road used to plot its way through the jungle?
DM: Maybe you do. Check History at 20.
DM: (Quietly noting another success.) There was this map of Ancient Belarsana that had a trade route along the Sana River, which should be near here. It should wind you toward a mountain pass that you might be able to see, if not for the trees.
The DM here is just going with the flow, and leaving mechanics in the background. Even noting the progress toward the skill challenge should be handled quietly, but give feedback to the players in the form of narration, not numbers.
DM: As you trek carefully into the heart of the jungle, the remnants of the old road occasionally guide you, and you follow the river and head toward the mountain pass in the distance. The ground becomes very marshy and the jungle canopy gets dark and impenetrable, and there's a deep and ominous bellowing noise coming from the direction straight ahead. Following the river is no longer an option unless you want to find out what that bellowing is.*
You've presented the players with a new obstacle. They can't just use History and Perception again, even. If they choose to go through the swamp, you can hit them with a combat encounter. If they choose to go around, they will lose their way unless they get another success. But they're creative and will suggest things. Let them!
Also, you've hinted at something: them getting above the trees. Maybe they have a spell or power that lets them fly. Maybe someone wants to climb up and scout (Athletics check!). In any case, you're concentrating on narration and not on the dice.