There is no greater enjoyment than to do Torah and Mitzvos with Cheshek (enthusiasm) and with a Bren (fire).
One of the great Tzadikim used to say, “If only the sinners would know how much joy he has when doing a Mitzvah, they’ll knock off my door to learn from me.”
Enthusiasm can really change a person’s day and infuse every moment with aliveness and closeness to Hashem. Instead of conducting one’s day in a mode of emotional reaction to circumstance and to people, when one conducts their day with enthusiasm they are proactive and brimming with zeal and excitement.
The holy Barditchever zy”a explains this very important Yesod in the name of the Ba’al Shem Tov.
The Tachlis – the purpose of the whole world is to make a Nachas Ruach to Hashem by doing Torah and Mitzvos with the proper intention, which is to make a Nachas Ruach to Hashem. For this reason, the main thing for us is to do the Torah and Mitzvos with Hislahavos and enthusiasm. Because the more intention we have to make a Nachas Ruach for Hashem, the more excited we will be.
Sometimes a person can do a Mitzvah for reasons other than making a Nachas Ruach to Hashem. For example, doing Mitzvos by rote or just enjoying learning or doing Chesed, etc. When a person does a Mitzvah with a Bren and enthusiasm, then their main goal in doing the Mitzvah is to make a Nachas Ruach for Hashem.
This does not mean that one should not enjoy doing Mitzvos and do it only as a sacrifice for the sake of Hashem. The opposite is true. The more one enjoys and is enthusiastic to do a Mitzvah, the more Nachas Ruach it brings to Hashem.
The Barditchever continues, when a person does everything in their day to make a Nachas Ruach for Hashem, the Shechinah is revealed in whatever they do and that brings much success in their endeavors.