How many calories, carbs and grams of fat should I have per day?

Male, 5’10, 140lbs. I’m pretty thin and would rather not gain weight as I grow older and my metabolism slows down. I don’t want to turn into a carb/calorie counting freak, but I’d love to know what ballpark of daily calories, carbs, and grams of fat I should be keeping under in order to keep my current weight.

Thanks for any insight!