Bribe with the promise of something else more exciting. I say "Ds, if you help mummy tidy this away you can get x out". Or if we're planning on doing something anyway that I know ds likes I say "Ds, do you want to see your cousin?" And when he says yes I say, "ok, then help me do this first and we can go and see her!" Honestly, bribery always works with him and i'm not ashamed of it!