A great place to start is by teaching your dog to be happy to get in and out of a crate and to stay in there (even if the door is open).
Also teach your dog to do the same behavior in a specific place that is more portable (for example, next to your backpack, or on a piece of clothing or rug) using the same techniques after they are good at learning to rest in their crate.
Start by: playing games where going into crate makes you throw the ball. Or throw treats into the crate and let your dog find them in there. Feed your dog dinner in the crate. Let him sleep in the crate at night etc.
Then teach them how to rest in there.
Here is an example of a very high drive dog learning to rest (and manage his arousal level so he can rest) in this video by playing the “it’s your choice” game in the crate.
Notice we are also working on orientation to his handler on exiting the crate as well.
Adding Distance, Duration and Distraction to this dog's basic understanding of staying in the crate until released start the process of building his self control, arousal management and ultimately expectation that when he’s in the crate its time to rest.