When I heard this mishna it sounded a lot like Tefillin, (which has a strap tied on our left arm from our "Father's" "right arm" -- I saw in a teaching of the Arizal, since we stand facing (figuratively) God, His right parallels our left.) and sure enough, the Talmud's only commentary is: and a sign [to understand and remember this] is Tefillin.
How can this help our avodat HaShem, our divine service?
(1) If we have an intense desire to be close to God and we're missing him too much, put on your Tefillin. Better yet, maybe help someone else who doesn't know how to put on Tefillin.
(2) If we want to have an intense desire to be close to God and we feel like that feeling is missing from our lives, put on your Tefillin. Explore Tefillin as a way to feel a deeper connection with HaShem, no matter where you are or where you're going. (Including helping someone else to put on Tefillin)
[The advantages to helping someone else put on Tefillin, or participate in any mitzwah, are numerous, bordering on limitless, which is why I suggested it. Perhaps we can go into it in another post.]