@Nanren888 thank you so much! got that: I can say I thank you from the bottom of my heart.

Relax deeply, completely, . No "heart" involved in relaxing in English, that I know of. . >>So can I say: I thank you from the bottom of my heart? Yes, you can say that. (I took the extra full stop out :) )

@Howard, sorry for troubling you. So can I say: I thank you from the bottom of my heart.?

@Howard, thanks for the help! I understood. So I should say "relax completely".

"From the bottom of my heart" is an expression of how genuinely and sincerely we want to show our gratitude. We don't use it with a command like "Relax". Perhaps you just want to say "Relax completely" or "Let go, unwind"?