How to cast to mixamo BPs

so i’m trying to implement a stamina system into my game, and it worked fine with the regular FPcharacter, but as i switched to mixamo characters, i could not have the ‘Left Shift’ input blueprint.
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So i tried to go to the mixamo master bp, and I could add it there, so I would just use a global variable to set my ‘isrunning’ and it’ll be fine. But the variable needs a target, self doesn’t work, and if i cast to ‘MixamoAnimBP_Adam’ i need an object, and i have no clue what that is.

Any help appreciated, thanks in advance.