Set your heart/mind on something/on doing something - Idioms by The Free Dictionary
set your heart/mind on something/on doing something
set your heart on something
COMMON If you set your heart on something, you decide that you want it very much and aim to achieve or obtain it. Note: The heart is traditionally regarded as the centre of the emotions. She'd set her heart on an acting career. She admits that when she saw the flat Jeremy had set his heart on, her first reaction was horror.
set your heart (or hopes) on have a strong desire for or to do.
set your heart on decide you very much want to have.
set your ˈheart/ˈmind on something/on doing something,
have your heart/mind ˈset on something/on doing something want something very much; want to do or achieve something very much: When she was a small girl, her heart was set on a horse of her own. ♢ He set his mind on becoming a doctor. ♢ I have my heart set on a new guitar.