רבי ישמעאל אומר
הוי קל לראש
מקבל את כל האדם בשמחה
Rabbi Ishmael  says:
Be humble to those above you
and calm with the young.
Receive [or: accept] all people with joy. 
Few as these words are, they have multiple translations and understandings.
Still, a common principle underlies them all:
Don’t disturb your own peace-of-mind.
This is very much in keeping with Patanjali’s opening statement on Yoga:
“Yoga is the quieting of the changes of consciousness.” 
Swami Satchidananda, z”l, confirms this:
“Things outside neither bind nor liberate you; only your attitude toward them…There’s nothing wrong with the world. You can make it a heaven or hell according to your approach.” 
In short, both Patanjali and Rabbi Yishmael/Ishmael are telling us: When we get upset over a situation — over interactions with other people in particular — we must recognize that it is we, ourselves — not they — who are upsetting us.
“We create the world in which we live to a great extent. While many events are beyond our control and we are unable to have a direct influence on them, we still have the ability to [choose] our emotional attitudes towards a given situation…emotional consequences [on us] of an event are largely up to us.” 
There’s a whole field of psychology/psychotherapy based on this: Cognitive Behavioral Therapy (CBT):
“Therapists or computer-based programs use CBT techniques to help individuals challenge their patterns and beliefs and replace ‘errors in thinking such as overgeneralizing, magnifying negatives, minimizing positives and catastrophizing’ with ‘more realistic and effective thoughts, thus decreasing emotional distress and self-defeating behavior’.” 
And that is Rabbi Yishmael’s purpose precisely!
He wants us to know that “peace” is our natural state.
“Peace dwells unshakably in the heart of man as it dwells in the heart of nature.” 
Water will remain placid in a bowl — until we shake the bowl ourselves. How do we disturb our own peace of mind? Rabbi Pliskin tells us: By the thoughts we choose — however unknowingly — about the situations we face.
“‘[Torah says]…whether it is over an ox, a donkey, a sheep, a garment, or over any lost thing…’ 
[The Baal Shem Tov asked:] …how can it be that a body is born in purity…and yet the spirit can become involved in casting off the yoke (of Torah)?
The answer is [that the spirit allows itself to be effected] ‘over an ox’ — which symbolizes the evil inclination…’a donkey’ — which denotes coldness, for the Talmud teaches  that a donkey feels cold even in the summer season [i.e. G-d’s “warmth” is always present, but the spirit ignores It and feels “cold”]; …’a sheep’ — denoting scattered sheep, in the sense that a person scatters himself over everything, desiring everything and finding everything ‘necessary’; ‘a garment’ — denoting the coverings or garments [k’lipot — coverings that obscure the spiritual essence of things];…through this, everything is lost, including one’s own inner stability’.” 
Rabbi Yishmael urges us rediscover our own essential peacefulness and to avoid doing anything — especially with regard to others — that upsets our own peace.
 Pirkei Avot 3:16 (elsewhere 3:12, etc.)
 Yoga Sutras 1:2
“The restraint of the modifications of mindstuff is Yoga.”
“Yoga is the control (nirodhah: regulation, channeling, mastery, integration, coordination, stilling, quieting, setting aside, [restraint]) of the modifications ([changes in] gross and subtle thought patterns) of the mind field [chit: consciousness].”
Orit Sen Gupta’s Hebrew version יוגה היא השקטת הפעילות המנטלית means: “Yoga is the quieting of mental activity.”
 Swami Satchidananda; The Yoga Sutras of Patanjali; p. 48
 Pliskin, Rabbi Zelig; Gateway to Happiness; © 1983 by Rabbi Zelig Pliskin (later editions by others); p. 48-9
 Lichtenstein, Rabbi Morris; Jewish Science and Health; p. 161
 Sh’mot/Ex. 22:9
 Shabbat 53a
 Dvorkes, Rabbi Yishiahu Aryeh and Joshua Dvorkes; The Baal Shem Tov on Pirkey Avoth; Charles Wengrov, trans.; © 1974 by Rabbi Y. A. Dvorkes; English translation distributed by Feldheim Publishers; p. 66-7