For now, give the appropriate energy, respond with the appropriate response. This is how we learn. Soon you may develop your own ideas of what it is and how it works for you. In the usual sense of physical attack and physical defense, no. In the larger sense I use it every day.
Self defense is a side effect of something far more profound.
Aikido, the Way of Harmony, is a path well worth following. And it can be followed for a lifetime. So I always go out of my way to avoid an altercation. Having this attitude is probably the reason why, to this day, I have never had to use karate in an aggressive manner off the mat.