To me "Follow Your Heart" means that in making a decision, my brain (?) is telling what I SHOULD do, but my heart is telling me what I really WANT to do ... As UD said, following your heart may not always be the best thing ... but I think the decisions we look back on and question were the ones where we followed our head instead of our heart, and we wonder "what would have happened if....?" But, of course, that question can be asked about any decision we make ...
Scott, you mentioned how one's desires may not be the best thing to do in the "big picture", and that is certainly something that needs to be considered.... I think too often in today's society decisions are made for what is best for ME, at this point in time ... I feel there is not enough thought given to "What affect will what I do now have in one week, year, 5 years??? ...."

Sometimes in life we make decisions for ourselves, but othertimes we have to make decisions based on our love of others ...

Ah, life ... one decision after another ... I've often wondered what life would have been like if only Eve hadn't wanted that fruit salad ... (Speaking of life altering decisions!!!) .....
I wish you the best, my friend, and may you live comfortably with the decisions you make ...
t.