Method of operating earth-boring tools may involve activating a selectively activatable hydraulic fracturing device secured to the earth-boring tool to impact an underlying earth formation with a fluid from the selectively activatable hydraulic fracturing device. A crack may be at least one of initiated or propagated in a portion of the underlying earth formation utilizing the fluid in response to activation of the selectively activatable hydraulic fracturing device. The selectively activatable hydraulic fracturing device may be subsequently deactivated. Earth-boring tools may include a selectively activatable hydraulic fracturing device configured to transition between an activated state in which fluid is permitted to flow through the selectively activatable hydraulic fracturing device to engage with an underlying earth formation and a deactivated state in which fluid does not flow through the selectively activatable hydraulic fracturing device. The selectively activatable hydraulic fracturing device may be configured to at least one of initiate or propagate cracks.