Here the author refers to himself by his "heart" to emphasize his feelings. See how you translated this in [Ecclesiastes 1:17](../01/16.md). AT: "I applied myself" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
Possible meanings are 1) "the work that God does under the sun" or 2) "the work that God allows people to do under the sun." (See: [[rc://en/ta/man/translate/figs-activepassive]])
This refers to things that are done on earth. See how you translated this in [Ecclesiastes 1:3](../01/01.md). AT: "on the earth" (See: [[rc://en/ta/man/translate/figs-idiom]])