> How to get over this bred desire to work on everything of interest, and instead focus on one area? >
Why on earth would you want to get over your "bred desire"? We all know very talented people who spend many years working in a narrow direction, doing hard things, but their papers are read by almost no one (sometimes not even by referees who recommend acceptance, but that is another story...). When I was younger I would work on ten problems at a time, figuring that batting .100 was fine. Now I am down to four or five, so I have to bat a higher number, but I would never work on only one. I have great respect for people who devote years to solving one important problem (Wiles and Enflo come to mind), but for every successful mathematician like that I can name many others who have reduced their productivity by being too narrowly focused.