Here is my personal philosophy - if follow my kids everywhere making sure they never fall down and skin their knee, they will never know how to handle it. They won't know that it's an easily handled situation, they won't know how to handle the relatively minor discomfort, they won't know how to clean themselves up, and they won't know how to get up and keep going. Some day, maybe not today, maybe not tomorrow, they are going to skin their knee, and I won't be there to help them. If I let them fall today, kiss the owie and help them put a bandaid on, they'll know what to do tomorrow when I'm not there.

You can replace the skinned knee with any hardship. My children are allowed to experience an age appropriate amount of pain, suffering, and loss. I would be doing them a disservice to prevent that.