Lol so you want to make me puke 
@op
Normally the walk cycle animation you use already has a somewhat decent up and down motion to levarage - which normally you do your best to exclude so that people don’t throw up when playing your game.
Authoring animations for it is complex, the best way is to add a bone to your face, think of it like Pinocchio’s nose.
You set that nose tip to a fixed spot at about 10m distance, and you author the animation so that whatever the head needs to do is done in order to preserve that position.
Any vibration or movement in that spot will automatically cause a bone attached camera to give you a variety of nauseating episodes.
Increasing that focal point distance will lessen the bounce and make the animations less prone to giving you problems.
In Blender, bone paths are a decent way to determine even small movements at a glance.
For full body immersive games, this process is pretty much required. And/or you just go with a camera that isnt attached to a bone, so people don’t get sick…
And if you do that, then Everynone’s solution has you covered - except maybe shake it less…