Should I speak out with my heart or mind?

This is just a thought in my mind infact can say a question with no answer, which is been haunting me till date !

According to me there are two ways to speak to any one...... "speaking out my heart" and "speaking out my mind". Both of these could be same some times or both of them can be different sometimes.

I find myself not speaking out my heart at times rather find speaking out my mind. Is it always better to speak out my heart or speak out my mind. Either it be love , my career making , decision making or for that reason even petty things, I try hard to act upon the way I feel I have to do. But sometimes there is a fear factor which makes me take a step back, this fear is about loosing something or someone. At such situation I often act out which overwhelms me or the other person at that very moment, it would be only for one reason "I wouldn't like to hurt the person". But this action would be contra of what my heart says rather say I often speak out my mind, better way or easy way to tackle the situations.

How am I suppose to tackle such situations? , should I act out as my heart says or should i mask up myself as a good person and act out not hurting others, as my mind says !
In couple of occasions when I have tried speaking out my heart, I have literally hurt few "As people say truth is always bitter" !
In few other occasions when I have tried speaking out my mind, I would have put the person to a very comfortable feel and that would got a step closer to the person. But at the same time its in a way I am misleading a person, which is absolutely sounds overwhelming to the person, thats what I mean that the person is not hurt by your remarks or suggestions. Most of the times this happens when people are very egoist or are not ready to accept the truth or facts with them. Sometimes even I could be wrong !!!!!

Is it a right way to live ? why so something which you don't feel like doing but still do for the sake of others. Hope to find answer soon ..............!