This might seem an overkill for the OP but it's really useful to deeply track your productivity: RescueTime.
It's supported on Linux (besides Mac/Windows). You install a small application that stays in your tray and it tracks all your windows, generating later a report on your productivity.
It can automatically categorize a LOT of applications, and for those he understands wrong or doesn't know, you can set what the window means: very productive, productive, neutral, distracting or very distracting. That sums up to a productivity score for your day. You can also ignore some applications that has no actual meaning and you spend very little time on (such as Nautilus/Caja).
There's a paid version that adds features such as offline time tracking (you can manually enter what you did, such as meetings or client calls, the app asks what you were doing when your computer was idle!!!!), Zapier integrations, even deeper statistics and other stuff I don't actually know because I didn't use the paid version after the trial :)
This was the only application that really helped me stay focused - because I was afraid of receiving that dreaded email by Sunday morning saying I was unproductive D: