*You're their hero. Little girls love their daddy. Little boys want to be like their daddy. They will do whatever they can to impress you. Roll with it, and enjoy it because it won't last forever (thankfully my two are still in this phase).
For godsake spend time with them. Even if it's something mind-numblingly dull like doing the same 12 piece jigsaw you have already don't 50 times with them. All they want is your company.
Abandon any strategy you think you have. As the saying goes "no battle plan survives contact with the enemy", well, "no parenting plan survives contact with the child". You might think you'll never let your kid stay up late, you will. You might think you will never yell at your kid - you will. You might think you'll spend all day every day doing what they want - you won't.
Let them make mistakes. Including hurting themselves (not too badly, obviously). If you've told them that they shouldn't try to jump between couches, and they insist on doing it, LET THEM. That way, when they slam into the floor and cry, they'll know not to do that any more. If you keep stopping them, they'll just see it as you ruining their fun and want to do it more (obviously engage common sense with this one. Don't just let them touch the stove or run out into traffic etc).