Carson says

(The issue) is service of real people. The question is 'how can i be most useful?', not 'how can i feel most useful?', the goal is 'how can i best glorify God by serving His people?', not 'how can i feel most comfortable and appreciated whilst in some form of acceptable Christian ministry?', the assumption is 'how shall the Christian service to which God calls me be enhanced by my daily death, by my principled commitment to take up my cross daily and die?' not 'How shall the form of service i am considering enhance my career?'

--A Call To Spiritual Reformation, D.A Carson, P83

Real challenges as i start a year of 'full time Christian work'.