A Top 10 Tough Challenge

I am working on a list of 10 hard things in anticipation of a series of lessons that Adam Markle and I will be teaching soon.  I would really like to hear what everyone out there thinks about the tough things God asks of us.  To prime the pumps I am going to say that one of the toughest things we are called to do is live in community with one another.  We are so diverse and unique that it is hard for two people to live together- much less a congregation of 180.  However, for some reason God calls us to live in community and do so with unity and peace.  Not easy... what are your thoughts?  What has God asked of us that is tough?