I’ve got a new shtick that I’ve been doing lately. When I help someone to put on tefillin, I try to immortalize the moment for posterity. After he’s finished praying, while still strapped up, I pull out my iPhone and ask him to pose for a photo. If his family are there at the time, even better; I get them to all cluster around their husband or father and smile for the camera.

I’m not collecting trophies or notches on my belt; the real reason I go to this trouble is so I can then email the proud snaps to the people in question.

They love it. They show the photos to their grandparents and post them on their Facebook walls. They forward the happy shot for their wives’ approval and remind me of the moment the next time we meet. Hopefully, this photo will start a conversation, and their kids will remember that “those black boxes that Daddy put on at the shopping center” are relevant to their lives as well.

It’s the same with every mitzvah that people accept on themselves. People don’t just put up a sukkah for their own family; they invite their friends to come by and share the fun.

As soon as a new family start coming to shul regularly, they start nudging their extended family to join. Just last week someone was telling me that the best part of owning a lulav and etrog set was getting to watch his 8-year-old daughter teach her whole class how to shake it as well.

If you think about it, it’s this model that has ensured that brit, the most “successful” mitzvah of all, continues to be so universally accepted. On the face of things, it just doesn’t make sense. Of all the 613 commandments that G‑d gifted us with, submitting your 8-day-old son to elective surgery would have to be the single most difficult act that one can imagine volunteering for. Why would millions of otherwise rational parents have proven so dedicated to such a hard act to follow?

From a mystical perspective, we explain that brit is a covenant. When G‑d first commanded Abraham to circumcise his son, He promised him: “I will make a covenant with you forever and multiply you exceedingly (Genesis 17:2).” A covenant cannot be broken. A covenant cannot be abnegated or abrogated. A covenant is forever. You are hard-wired to circumcision; your soul won’t allow you to opt out.

However, even on a more prosaic level, we can still understand why people keep on circumcising. If every boy has one, then circumcision has become the norm. It’s no longer a matter for debate or conjecture; it’s just a given that a Jew needs a circumcision and a Jewish parent will circumcise his or her son. They may not enjoy it, they may even dread the prospect, but they’ll do it because that’s just what we do and we can’t imagine any other possibility.

The more often that people do something, the more normal it becomes. When one Jew shakes a lulav and etrog or straps on tefillin in public, it normalizes the experience for others. When you see your neighbor has candles shining in her window this Friday, there’s a far greater likelihood that your house will soon also be lit up with the radiance of Shabbat.

In addition to their innate worth as independant connectors to G‑d, mitzvahs are contagious. Judaism is not just meaningful, it’s fun. When we do the right thing and we show that we’re proud to do so, then we inspire our families and friends to buy in.

And together, we will change the world.