Pawn Velocity In blueprints

Hi I am Having an issue at the moment where i cannot change a pawns velocity using the Blueprints. i have the animations set up and ready and all the other blueprint and behavior trees are working the way i wanted. My goal was to have the pawn change speed into a sprint when it see’s the player. so far he moves to the player when he see’s them and even forgets the player when you move far enough away, but the issue is that i cant think how to change the velocity of the pawn to a set value when(in the behavior tree) the player is seen. I have a blueprint set up ready so that it will set a “is Sprinting variable” to true. any further is where i get stuck, any help?