In Khmer to encourage someone is to lift up their heart,
and when your heart is down it means you are sad.
Its pretty similar in English, but other heart phrases are opposite.
If you have a big heart in Khmer it means you are proud,
whereas in English is to do with kindness.
Someone with a hot heart is a bad person, but in English a warm hearted person is someone you want to be around.
A heavy heart in Khmer means you are persevering, while a light heart means you aren't standing your ground. Maybe like a feather in the wind, it is light so it gets blown around easily, while a heavy rock will stand firm.
A Chinese friend shared this with me after reading the previous one on Khmer hearts:
In Chinese, if you have no heart means you are careless;
if your heart is small means you are careful;
if your heart is black in colour means you curse someone;
if your heart is open means you are very happy.