at pains, be at

be at pains

To put forth effort toward some goal or end. Annabelle is at pains to make sure her relatives are comfortable when they come to visit. So far, she's cleaned the whole house and set up all the guest rooms.
See also: pain

at pains, be at

Also, take pains. Make a special effort or take extra trouble to do something. For example, Bob was at pains to make a good first impression and wore his best suit, or Mary took pains to make sure her speech would interest the audience. [First half of 1500s]