Just stop it.
Everyone does it, so don't pretend that you don't. Even if your password is really good (like 7 letters and 7 random numbers like my go-to password), STOP USING THE SAME PASSWORD FOR EVERYTHING. Here's why.
If someone were to break into one of your accounts - say, your email - they would literally have access to everything. Bank accounts, credit cards, Amazon, eBay, and then even more stuff like your iCloud or Google Play account, where they could wipe your phone or even your computer. There are two things that you can do today to make it exponentially harder for someone to compromise your digital life.
1. Use two-factor (or two-step) authentication. Google and Apple both now offer 2FA as a way for you to add an extra layer of security to your accounts. Basically, it works like this: you must have a a device on an account that you physically have access to and when someone unauthorized requests access, you must approve it. Google Authenticator is the app for this (iOS, Google Play) and Apple will let you enable this over Apple.com in your iCloud account.
2. Use an app. This may be the better and easier solution of the two, and you may not even want to fiddle with 2FA. There are a few apps that allow you to generate and save unique passwords for all your accounts, and keeps them safely encyrpted either on their own servers or on your own Dropbox. The app I love for this is 1Password. Their apps are a little pricey, but so worth it when you think about what you could lose if your accounts are compromised. Right now, for my four main accounts (Google, Apple, Twitter, Facebook) I have four 16-digit random passwords. And 1Password keeps track of all of them with a really great app. All I need to remember is my 1Password Master password and I'm set. LastPass is very good too and does a lot of the same things. Both apps have Safari and Chrome extentions.
So, in 2014, resolved to NOT use the same passwords for everything. Because if you do, you're asking for lots of trouble.