DS is 4 and can be a real angel much of the time but the one behaviour we can't seem to manage is his aggression. We have previously used the naughty step but spent most of the time chasing him around the house whilst he threw anything he could get to hand finding it all highly amusing, we've used his bedroom as he can't really do any damage to anything in there but this was reliant on us holding the door to stop him getting out. We've tried withdrawing ourselves from the situation and completely ignoring him but again this is a battle as we hold the doors to stop him getting in (and throwing stuff at us). I don't feel that holding doors shut is the right way to go about time out but don't know what else to do. We've gone back to time out on a mat today and have had up to 45 mins of either chasing him or restraining him (as he tries to punch, kick, bite etc. until he does his 4 mins. All other behaviours we manage quite well with distracting/stickers/positive prasie etc. and i don't know whether this is just the hard bit we have to go through as part of zero tolerance to his aggressive behaviour and its about persisting but I'm worried that we're just not dealing with things well at all. I'm also aware that as we try different techniques we're not being consistent which isn't helping. Please help!