I'm currently training a student (rating: ~1350 ELO, Age: 16) in my local chess club, who has been making quite some progress in his rating and playing style lately. Nevertheless, when he is playing against me or another much higher rated opponent (1700+ ELO), he always plays quite cowardly and defensively and isn't going for an attack even if it is objectively good for him. Therefore, he is quite happy when he draws a game against a higher rated player instead of taking a little risk to win a game.
How can I access this psychological problem in my training sessions and teach him some courage?