What do you call a person who is constantly busy with his or her workload but is willing to go the extra mile to do more than what is needed? Is hardworking good enough or is there some other better words that could be used to describe this person?
This one is off by a little, but if paired with one of the other ones it could give it that extra jolt of flavor.
1) Careful and hard-working. Thorough and assiduous. Involving or taking great care; painstaking; diligent.
a conscientious worker / a conscientious pupil / conscientious application to the work at hand / Al admitted that he had not been taking his work seriously and realized that he should be more conscientious about his job or he would be discharged. / She is generally very conscientious about her work. / No president who performs his duties faithfully and conscientiously can have any leisure.
2) Guided by or in accordance with the dictates of conscience; principled.