Entregarse en cuerpo y alma

[ROBINDESBOIS]

English?

[Perikles]

To devote oneself in body and soul

[JPablo]

Also, To devote oneself wholeheartedly and to put your whole heart and soul [into the task] :)

[Perikles]

Also, To devote oneself wholeheartedly and to put your whole heart and soul [into the task] :)
Yes, that's better than my suggestion. :thumbsup:
(yours is more appropriate for a task - I was thinking more specifically of human relationship)