immediate punishment at the first sign of refusal. 

There is a place and time for self determination and independent thinking. Sadly that place and time is not in front of your parents when you're three. 

Giving chances and being lenient just teaches him that you really aren't serious about anything until you get mad about it and act. 

Things get alot easier when they know you always mean business. 

To clarify to the weirdos out there : I'm not talking about pain compliance. I'm talking about either removal of dopamine inducing items (toys and TV) or temporary restrictions on movements (time outs).