An adjustable exercise device that includes one or more inclined riser blocks for readily elevating and inclining a platform to enable stepping and other exercises to be readily performed on an inclined platform. The inclined riser blocks may be matingly engageable with the bottom of the platform to elevate and incline the platform. The inclined riser block may include a top face matingly engageable with the bottom of the platform, a bottom face, and a central portion extending between the bottom and top faces and having a front and rear, the central portion increasing in thickness from the front to the rear. The top face extends at an incline.