From my personal experience, you need motivation and enthusiasm to get in the zone. Every morning after my prayers, I always do some house chores before hitting the office. I may clean the counter, take out the garbage or work out with my weights. After this happens, I am already in the zone. Keep in mind, everyone is different and will have different stamina, but it is important to do body exercises to get in the zone as laziness and not moving around leads to tiredness. It is all a process of mind over matter.