As a priest if I decide that I no longer want to do something, such as work in a specific parish, do I have any say or is it all out of my hands?

You need to keep two ideas clearly in mind and in balance when it comes to your work assignments as a priest. The first is obedience to one’s Ordinary (bishop or religious superior). The second is representation. Ideally, both the Ordinary and the priest seek God’s will. For your Ordinary to make a good decision with regard to your mission, he needs to know you well. He should understand your wishes and desires and appreciate your gifts and talents as well as your weaknesses and limitations. He should take all of this into account when he assigns you to a particular location or ministry.

Of course you may have a good reason to request a particular appointment or to reject another. You should make your bishop or superior aware of your reasons, so he can take them into consideration in coming to his decision. The bottom line is that, because of your commitment to obedience, you should accept in faith his final decision. Nevertheless, the situation can always be revisited if new information or circumstances come to light.

Decisions once taken can be reviewed when new information or new insights emerge.