What are some daily difficulties you have with your toddlers?

I was just wondering all children seem to have their misbehaving niche in life some children bite, others kick, and others hit. What are some of the daily behaviors that your toddler has that you just can't seem to get through to them that it's not right and allowed? For example, my two year old son (almost 2 1/2) has gotten into the hitting at habit he knows it's wrong but in the heat of the moment it seems all he wants to do and i repeat over and over that he needs to stop. In other words will it be this way forever? I'm starting to wonder if I will have a nine year old child hitting at me.