[header] How to do an oblique sit up [title] Lay your exercise mat down. [step] Unroll your exercise mat and lay it flat on the floor. An exercise mat will provide comfortable cushioning between you and the floor and will also absorb some of the impact. 
[title] Lie on your back on the mat. [step] Lay down flat with slightly bent knees and make sure that your feet are flat on the mat.