B.G 6.36

असंयतात्मना योगो दुष्प्राप इति मे मतिः। वश्यात्मना तु यतता शक्योऽवाप्तुमुपायतः ॥३६॥

asaṁyatātmanā yogo duṣprāpa iti me matiḥ। vaśyātmanā tu yatatā śakyo'vāptumupāyataḥ ॥36॥

[ असंयत आत्मना योगो दुष्प्राप इति मे मतिः। वश्य आत्मना तु यतता शक्यः अवाप्तुम् उपायतः॥
असंयत (asaṁyata) - uncontrolled; आत्मना (ātmanā) - by the self; योगः (yogaḥ) - yoga; दुष्प्रापः (duṣprāpaḥ) - difficult to attain; इति (iti) - thus; मे (me) - my; मतिः (matiḥ) - opinion; वश्य (vaśya) - controlled; आत्मना (ātmanā) - by the self; तु (tu) - but; यतता (yatatā) - by the striving one; शक्यः (śakyaḥ) - possible; अवाप्तुम् (avāptum) - to attain; उपायतः (upāyataḥ) - by proper means;]

In my opinion, Yoga is difficult to attain by those who lack self control. However, it can be achieved through proper methods by those who are striving and have self-discipline.