Both Detective and SWAT take time to enter. They are not entry-level position, but they can me lateral. That means that some teams and agencies will hire people directly into those positions if they have government or military experience such as Special Forces Operators getting out and joining a SWAT team. Taking the initiative to get ahead however is admirable. Physical fitness is a high priority for SWAT, but not as much for Detective. Both require sound decision making skills. If you are looking at which academic courses will help you achieve Detective I would suggest; Forensic Science, Criminal Justice (anything), Ethics, an advanced Math, Economics or Accounting, and Technical Writing. These are of course the college courses to consider. For High School look into Language Arts, a Foreign Language (Spanish is highly recommended), any type of advanced Algebra or Geometry, and Biological Sciences.