There’s a great article called How to Focus. I could read it all at once without getting distracted. Can you do that, too? 
Here’s the gist:
Here’s how to focus:
- Focus is a muscle: The more time you spend focusing, the better at it you will get. Don’t give up.
- Clear your head: Got concerns? Write them down. Make a plan for how to conquer them. Then get to work.
- Location, location, location: Go where you know you’ll get stuff done where there are no distractions.
- Stop being reactive: Turn phone notifications off. No interruptions. It all starts and ends with you.
- Get your sleep: Or you’ll be dumb and impulsive. More sleep means better performance across the board.
A very fascinating quote from the article:
“Five years of reporting on attention have confirmed some home truths,” Gallagher reports. “[Among them is the notion that] ‘the idle mind is the devil’s workshop’ when you lose focus, your mind tends to fix on what could be wrong with your life instead of what’s right.”
My personal experience tells me that this is pretty much true. Being busy with important (rather than interesting, or urgent) stuff makes me happier and grants me a feeling of fulfilment.