How do you decide?

When you are faced with a weighty decision to make, you often use only two parts of you body...Your head or your heart. using your head usually involves giving serious thought to your decisions allowing facts and reason rather than sentiments to govern or decisions.  However, using our heart means just allowing our emotions or how we feel about a matter to guide us. which has had a long history of success? which has stood out against all odds and have resulted in contentment and happiness? well thought out decisions have always prevailed in my opinion.