Sit upright in a chair and position yourself close to the edge.
Position you feet hip width apart and place your unaffected foot on a small step.
Fold your arms so that they are not used to push up from the chair.
Lean your body forwards, and push through your legs to stand up straight.
As you stand, fully straighten your leg on the floor, whilst the leg on the step should remain slightly bent.
As this becomes easier, you may raise the step height.