That is, not just because you have to, but because you freely choose to. It's something that rises from a willing heart. That's the kind of attitude you must encourage and pray for in your leaders. Spontaneous and generous service from a willing heart. Encourage your pastors to have this attitude.
Churches can sometimes want pastors to fit into a mould.
They must do this, this and this, in the way we tell them. That stifles willingness. The temptation to do things just because we have to comes to anyone involved in ministry. Not just full-time pastors. It affects everyone from Youth group leaders to Archbishops.