Despite the fact that I use really long passwords and two-factor authentication wherever it's available I still worry that someone might break into my online accounts. And, my greatest worry is my Google Mail account.
In fact, everyone should be worrying about their online email accounts because they are the Achilles' Heel of your online identity. So much information passes through your personal email that it's a gold-mine for a hacker. Just imagine what could be done with the information on your online email account. Think of all the password reminders and password reset messages: access to your email means that an attacker could likely access many other accounts you own.
So, for my email I built in a canary: a tempting looking email that's sitting in my inbox that's entirely fake and designed to tempt an attacker into clicking on it. Here's a shot of my inbox: