Same problem here, and I suspect it's to do with having difficulty making the transition from inside-on-the-computer to outside-and-doing-enjoyable-activities. The only thing that works for me is to set a timer when I'm on the computer and force myself to get off the computer when the timer goes. Alternately, I'll use the computer clock to decide a time to finish, and make myself stick to that. If I go on the computer for "just a little while" rather than a pre-specified amount of time, I can waste hours.
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Music Theory 101: Cadences.
Authentic cadence: V-I
Plagal cadence: IV-I
Deceptive cadence: V- ANYTHING BUT I ! !! !
Beethoven cadence: V-I-V-I-V-V-V-I-I-I-I-I-I-I-I-I-I-I
-I-I-I-I-I-I-I-I! I! I! I I I