Enchiridion 23

If it should ever happen to you that you turn to externals with a view to pleasing someone, rest assured that you have lost your plan of life. Be content, therefore, in everything to be a philosopher, and if you wish also to be taken for one, show to yourself that you are one, and you will be able to accomplish it.

Epictetus, Enchiridion 23, translated by W. A. Oldfather

If it should ever happen to you to be turned to externals in order to please some person, you must know that you have lost your purpose in life. Be satisfied then in every thing with being a philosopher; and if you wish to seem also to any person to be a philosopher, appear so to yourself, and you will be able to do this.

Epictetus, Enchiridion 23, translated by George Long

If it ever happen to you to be diverted to things outside, so that you desire to please another, know that you have lost your life's plan. Be content then always to be a philosopher; if you wish to be regarded as one too, show yourself that you are one and you will be able to achieve it.

Epictetus, Enchiridion 23, translated by P. E. Matheson