Is your Gmail account nearly full? If it is you can either purchase more space or go through and individually delete every cat picture attachment. Alternatively, you can use a clever Google Docs trick shared by tech blog Digital Inspiration to sort your Gmail messages by size and quickly delete space-hogging junk.
We've covered web apps that do this before, but if you're uncomfortable granting access to a third party, this method keeps everything within the Google ecosystem. It's a pretty simple four-step process that first links Google Docs and your Gmail together. Once that's granted, it then creates a spreadsheet of all your big messages. When it's done you can sort by size and start cleaning out those data hogs with a couple of clicks, no third-party authorisation required. Hit up the Digital Inspiration for a sample spreadsheet and full guide to running through this for yourself.
Sort your Gmail Messages by Size using Google Docs [Digital Inspiration]