The Ibn Ezra says that the reason why a Nazir has to bring a Korban Sh’lamim is to show his contentment and joy since he was Zoche to fulfill his vow. Look how an Oved Hashem has to always be happy over his accomplishments in Avodas Hashem. You don't just make a Kabala (resolution) and keep it. You make a special party thanking Hashem for our success! Human nature is to kvetch over Aveiros, but being happy over Mitzvos isn't always so common. Kvetching over sins is the Yetzer Hara; not the Yetzer Tov! Believe it or not!
Your Happiness Level for Your Mitzvos Should Be Higher Than Your Regret for Your Aveiros
I was told that in Novardok they made a big party when they kept their Kabalos (resolutions). Notice how a Nazir has such a fancy name, as if he has a crown on his head. When you call yourself a Melech, you feel good about yourself! And growing long hair symbolizes your superiority to other people who don't control themselves! RSRH Zatzal says that hair symbolizes the body's insulation against the outside world, since it protects the skin against the elements.
By letting the hair grow, the Nazir creates a barrier against the outside world. Besides the: אַּיִל ram (i.e., a large sheep) he brought for a Shelamim, he also brought a כֶּ בֶּ ש sheep for an Olah, and a כַּ בְ ש ה sheep for a Chatas. The Ramban says that the Chatas is for not doing more Nezirus (self-control). Notice how the Chatas is just a sheep and the Sh’lamim is a more expensive: אַּיִל ram. Make sure your happiness level for your Mitzvos is much higher than your regret level for your Aveiros.
Look how much Simcha and dignity and good feelings surround the Oved Hashem; being called a Melech and feeling superior to others, with his long hair and with bringing an: אַּיִל ram (i.e., a large sheep) for a Sh’lamim to show his Simcha for completing his Kabala (resolution).
People don’t even Chap how lucky they are in so many ways. They don’t enjoy the sun and the air, their food and their health, even their Ruchaniyus (albeit small). All they think about is getting rid of the issue which bothers them
