Well there are many ways even a non believer can get benefited.
There are many management principles in gita, some of the samples are:
कर्मण्येवाधिकारस्ते मा फलेषु कदाचन।
मा कर्मफलहेतुर्भूर्मा ते सङ्गोऽस्त्वकर्मणि।।2.47।।
Meaning: But thou hast only the right to work, but none to the fruit thereof. Let not then the fruit of thy action be thy motive; nor yet be thou enamored of inaction.
It gives how we can get strayed away.
ध्यायतो विषयान्पुंसः सङ्गस्तेषूपजायते।
सङ्गात् संजायते कामः कामात्क्रोधोऽभिजायते।।2.62।।
क्रोधाद्भवति संमोहः संमोहात्स्मृतिविभ्रमः।
स्मृतिभ्रंशाद् बुद्धिनाशो बुद्धिनाशात्प्रणश्यति।।2.63।।
Meaning: When a man dwells on the objects of sense, he creates an attraction for them; attraction develops into desire, and desire breeds anger. (2.62)
Anger induces delusion; delusion, loss of memory; through loss of memory, reason is shattered; and loss of reason leads to destruction. (2.63)
इन्द्रियाणां हि चरतां यन्मनोऽनुविधीयते।
तदस्य हरति प्रज्ञां वायुर्नावमिवाम्भसि।।2.67।।
Meaning: As a ship at sea is tossed by the tempest, so the reason is carried away by the mind when preyed upon by straying senses.
Thus by carefully understanding these verses & applying in our life, any one can get benefited.