The Bar or Bas Mitzvah, while possibly feeling nervous about reading the Torah or giving a speech, looks forward to this milestone with great anticipation. The family of the young adult plans the Simcha, the celebration, hoping that all can share in their time of joy. There is a natural Simcha experienced upon a young person becoming a Bar or Bas Mitzvah. This natural Simcha, like the Simcha of Bikkurim, is supposed to carry over and inspire the new adult to be happy and give thanks that he has now personally received the Torah. Furthermore, just as by Bikkurim, the Bar or Bas Mitzvah is a time for reflection for all who were involved with the youth, helping them be what they are today.
Much work goes into raising a child.
Parents must realize how much Hakaras haTov, appreciation and thanks, one has to have to Hashem for His hand in Chinuch HaBanim, child rearing. G-d gave it to you as a gift, and you should realize how precious this gift is, and therefore be thankful for getting it. You also have to appreciate all the work that went into bringing you to this occasion, and the time, effort, and money, that your parents spent to assure that you would reach your potential, and to assure that your Bar or Bas Mitzvah would be a time of Simcha, a Simcha that all would feel and that would inspire all.