Great that your profile name answers your question itself. Yes, the 'masti' and the feeling of enjoying the preparation mode is important!
Competitive examinations like National Defence Academy (NDA), can be qualified when you have the courage to deal them. Further you'll need an attitude which the defence personnel call, 'OLQ', Officer Like Qualities, once you clear the written and go for SSB (Service Selection Board). This is where your actual test will begin. You will be examined on each ground, endurance, patience, responsibility, accountability, logic, intellect, etc. You can pass these tests too, if you don't take them as tough, what you always need is enjoying what you do.
So enjoy asking questions and getting them answered. Questioning is good, it's cool.