An exercise device for use by a user on a support surface comprises a support assembly, an extendable neck, and one or more resilient first resistance assemblies. The support assembly supports the user relative to the support surface. The support assembly includes a support body that is engaged by the user, and a support base that supports the support body, the support base resting on the support surface. The extendable neck is movably coupled to the support assembly. More particularly, the extendable neck is selectively movable relative to the support assembly between a retracted position and an extended position. The one or more resilient first resistance assemblies are secured to the extendable neck.