You do this by attending several graduated short retreats that last a weekend, three days, a week, ten days, two weeks and a month. Once you know you can handle a weekend retreat comfortably then go to the next longer one. When you know you can handle that retreat easily, move on up to the next longer one. Sometimes even a weekend retreat is boring and painful if you are not prepared. Leave it behind.
People are generally unable to let go of their work.
They are used to their daily and weekly routines full of TV, company, gossip, uncontrolled eating, drink, drugs, sex, travel, etc. When they go for retreats they have to let go of most of these routines. Since they are accustomed to working under great pressure, even in retreats they are tense and anxious. They want to get something out of meditation as quickly as possible and then get back to their work. Try to think that you have left everything behind for a while and now you have all the time in the world.