Proactive and reactive mindsets: Traditional jiu jitsu was centered around a reactive mindset where you let an opponent take the initiative and you capitalized on mistakes he made during the match. In very long matches against less experienced opponents this works very well. In modern jiu jitsu with shorter duration and very well trained opponents there is generally a push towards a proactive mindset where you initiate and get an opponent following your lead. In truth there have been great champions using both methods, so I believe it's wrong to try to say one approach is inherently superior to the other. Try to develop both aspects into your game. When you are matched against much bigger and stronger opponents the reactive approach may well be better. As you age the reactive approach often gets better results. The proactive is best when you are matched evenly in size and skill. Ultimately you'll need both to fully develop your game, though it's natural that your personality will determine which of the two you favor – aggressive confident athletes typically favor the proactive approach and less assertive, patient or Underdog mentality types typically favor the reactive approach. So develop both, but recognize that you'll probably favor one over the other, but that different circumstances and advancing age may change your mind as to which you'd rather make use of
