Where Does the Time Go?

The age is coming....you know the one. the child is getting a little older, wanting to play every sport possible...things you didn't even know existed! So, I am just entering this world. I am really a little lost here. I mean, I want my kids to play everything, why would I say no to anything...right? But, at what point does it get to be too much? I mean, they are coming home from school and you are right out the door to go to this practice or that game. I wouldn't want to deprive them, but I do want some control and family time left. How do you balance it all.
I happen to have a wonderful resource, she has been through it recently, so she always has great tips for me. I think I may follow her advice, tweak it a little for my particular situation, but follow for the most part. She says one activity at a time and that particular activity cannot be more than 3 days a week. She has a child getting a little older who participated in a sport...5 days a week, games on the weekend, etc. How hectic! Wasn't the best experience! SO, I just started my first activity..and we are going to see how it goes! What a journey though and how exciting to see your children "playing on a team" etc. I can not wait!
Some ideas for activities don't even need to be costly..you can find things at your local library, church, gym, community center, local colleges, everywhere! You just have to look a little!
So, my question (click on comment below and let me know) is what is your advice and how do you handle all the hectic running, meanwhile, making it fair for all of the children in the house?