I would like to help myself control how many video games I play. Is there a way I can block Steam at certain times of day or after using it for so long?
Short of parental software, you could try either of these:
Take your steamapps folder, and compress (or store it (ie no compression) it using 7zip/winrar. Have someone you trust make up a password, and when you've finished working then have them unlock the archive. The steamapps holds your games if you didn't know.
Uninstall Steam, but keep the steamapps folder (%Steam Directory%/steamapps/). When you're done with your work simply reinstall Steam, and you start playing.
You can use GameNanny to control when you can play Games and when not. I never used and I actually don't want to encourage anyone to use since I do not know if this program is safe or not. It seems like that it is safe, due to many users using it. It also seems to be Open Source.
However, do use it at your own risk and make sure Steam Guard is on and your email account has a different, but secure password.