When everything is falling apart around you: pick one thing - one tiny thing - and do it. More often than not, it's just the impetus you need to get into something bigger. Sometimes it's all you can actually do, and you'll at least have done something, even if it's really small.
Isolate your senses to reduce the chances of distraction. When I need to be really productive, I go to a place with a lot of sensory constants (like a library): no one is cooking, so smells don't distract me; I'm in a cubical or closed room, so I only see a wall; I listen to the same song on repeat, which is basically like white noise after a while; there's nothing around me so I'm not tempted to touch anything new or interesting; I'm seated and don't have to move unless my body demands a change of scenery. The more senses you remove, the more distractions you remove. This is extraordinarily powerful; use only when absolutely necessary, as you will also lose track of time.
Create a to-do list. I suffer from what I call productive procrastination. I pick one item from my to-do list, and work on it until I get bored with it. Then, to procrastinate, I work on another item on the list. Rinse and repeat until all of the items are completed.
Pick up a new hobby. Believe it or not, chronic boredom will only make you less productive. Busy people stay busy because there are always things on their to-do list.
Give yourself permission to have fun, and get your butt in gear so that you can make the fun moments really count
Chose your hobbies wisely. Conversely, if you're overwhelmed by all the hobbies you have, let one go. Being overwhelmed means you're unable to act, and thus you can't be productive. Remember the critical saying: "every time you say 'yes' to something, you're automatically saying 'no' to something else."
Variety is the spice of life. Don't force yourself to do work all the time, but also don't let yourself do anything but work for too long. Give yourself permission to have fun, and get your butt in gear so that you can make the fun moments really count.