He is from the States. He was in Israel visiting his son who recently made Aliyah (became an Israeli citizen and now lives in the Land). He told me that he had not put on tefillin for some 40 years. I asked him why he stopped. He said that he only did it while he was in a Jewish school for a couple of years when he was obligated.
"When I didn't have to do it, I stopped."
"That's because they only taught you the obligation to put on tefillin. Had you also learned what happens spiritually when a Jew puts on tefillin you would still be doing it every day.
He nodded, pointed his finger at me, shook his head "Yes, yes" and said, "You're right."
Hashem gave us mitzvahs so we can grow in holiness. That is the exact wording we say in the blessings, "….Who has made us holy with His commandments."
He has commanded us to become holy so we will be able to recognize and emulate His holiness. But this awareness does not come automatically with the physical mitzvah. We have to "direct our hearts to Heaven."
Hashem is present everywhere at all times, but He hides. He hides to make us search for Him, and then, if we try hard enough we will gain the reward of finding Him.
Mitzvahs bring holiness… and when done properly they also bring great joy.