Not quite true. It all depends upon the objective and the goal. Certain things can be achieved only by doing things correctly with "perfection"(ideal) as the goal. The more difficult and forceful the activity the greater is the importance on "correctness" else the risk of serious injury and lack of progress towards a goal.

For example, merely waving your arms and legs around will not make you a Martial Artist. You need to focus on the core concepts, techniques and methods of practice. One can approach this with three different goals in mind;

a) For simple Health benefits - Here you take it as easy or as difficult as you want to maintain health. Eg. Taichi chuan.

b) For Competitive purposes - Here you focus on the correct execution of techniques according to some standard. "Perfection" is the goal here. Eg. Wushu competition

c) For some other ideal eg. Fighting in Martial Arts - This requires a different approach where you focus on power, strength, mental toughness etc. Eg. Muay Thai, MMA etc.

The point is that while you have to keep your motivation up, you still have to go through a "correct" process which may not be always "feel good and fun".