One of my favorite books about productivity is "Deep work
". It includes immersion methods that help to achieve incredible results. Actually, anyone can work only for 4 hours a day and complete the whole scope of tasks. The most important thing here is to avoid any distractions: unnecessary internet searching, social media, private and corporate messengers, etc. You should focus on the tasks and pay all your attention, all mental energy in doing them.
You can also use a method of a "nice gesture
". For example, you can work in an extraordinary, luxury place, or do something else unusual. Some writers who can't complete a novel, take a ticket on a flight or book an expensive hotel room for working there. As for me, I prefer to do my businesses not at the office, but at coworking on the other side of the city. Nobody knows me there, so nobody distracts me with the endless flow of questions, talks and unimportant tasks.
I also like one of the most famous time management methods, called Pomodoro
. It's really helpful for people, who can't be concentrated on something for a long time. In a few words, you should divide your time to intervals. For example, you work constantly without distractions, during 20 or 25 minutes. Then, you have breaks of 5-15 minutes.