at pains
(idiomatic, with infinitive) Making careful effort (to).
The agency has been at pains to stress that its decisions are still based on sound science.
He was at great pains to distance himself from the rumours.
Always, Sir, set a high value on spontaneous kindness. He whose inclination prompts him to cultivate your friendship of his own accord, will love you more than one whom you have been at pains to attach to you. Samuel Johnson
He is at pains to avoid making enemies. He is slow, but very methodical. He displays marked tactical ability, though he is inclined to spend overmuch time on his appreciation. Friedrich Paulus