Musar su Salmi 55:7

More important than everything else is solitude. For when he removes worldly matters from before his eyes, so too he removes lust for them from his heart. King David, peace be unto him, praised solitude saying: "Oh, that I had wings like a dove! I would fly away and be at rest; yes, I would wander far away; I would lodge in the wilderness forever" (Tehilim 55:7-8). And we find that the prophets Eliyahu and Elisha would set their dwelling place in the mountains due to their practice of solitude. And the early pious sages, of blessed memory, followed in their footsteps. For they found solitude to be the best path to acquire perfection in Separation, so that the vanities of their neighbors would not lead them to also become vain like them.

However, you must know that just like Purity of thought applies to the bodily deeds which are intrinsically near to the evil inclination, whereby Purity involves distancing the bodily deeds from the evil inclination such that they don't stem from it, so too Purity of thought applies to the good deeds which are near to the Creator, blessed be He, whereby, Purity involves not distancing from G-d and not stemming from the evil inclination. This is the matter of "not for the sake of the mitzva itself" (Shelo Lishma), mentioned frequently in the words of our sages, of blessed memory.