What follows is a short answer to your question. Even so, I hope it helps.
It is often the case that the same person thinks positively on some occasions, and negatively on other ones. So, to think positively is not necessarily at complete variance with thinking negatively because these two types of thinking greatly depend on what happens around us. Even so, for biological reasons, there are people who are more inclined to think positively and be in a good mood, extraverts for example, and other ones to think negatively and be in a bad mood, introverts, for instance. I am not sure that is always harder to think positively than negatively or the other way around. However, in the majority of cases it is preferable and hard to think positively than to think negatively. When the former is the case, we tend to be proactive such that a certain state of affairs is changed in the right direction. When the latter is the case, people tend to react instead of acting, and even to give up changing sad realities.
As a psychologist, I also think that to think positively is associated with optimism and, say, an internal locus of control. To think negatively is often associated with pessimism, learned helplessness and an external locus of control.
As for me, I conceive of myself as a moderate optimist and, say, a controlled pessimist. To think that we live in the best of the worlds (i.e., extreme optimism) can lead us to think that all is OK and, as such, we do not have to do anything for there is nothing to be ameliorated. To think that our world is in a situation of an unevitable catastrophe (i.e, extreme pessism) can lead us to think and there is nothing we can do to put an end to such a situation. As I see it, extreme optimism and extreme pessimism are two faces of the same reality. In the last analysis, both tend to lead to inaction and nihillism. So, the most wise perspective is to be, say, a moderate optimist and moderate pessimist and, accordingly, that there are times to think negatively and be pessimst and times to think positively and be optimist.
اعرف التفكير بــ:- نشاط نفسي معرفي يطلق على حركة المعلومات في الدماغ عند استقبال مثير للبحث عن المعنى في الموقف أو الخبرة . كما اننا لا نستطيع التوقف عن التفكير اذ ان حياة الفرد هي سلسلة من الإحداث والمواقف التي تتطلب التفكير . ويتكون التفكير من اللغة والمفاهيم والصور والقضية ( هي مفهوم مقترن بحكم, أواستناد مفهوم على مفهوم اخر. مثل, الإنسان كائن حي ) . وهذه العناصر الاربعة هي التي تحدد التفكير الايجابي او التفكير السلبي للانسان وخصوصا العنصر الرابع (القضية) اذا كانت مقترنة بالاخلاق فان تفكير الانسان يكون ايجابي اما اذا لم تقترن بالاخلاق فان تفكير الانسان يكون سلبي , ومن افضل البرامج لتعليم التفكير الايجابي البرامج الدينية المسيحية والاسلامية الحقيقية , وهناك احاديث كثيرة للمسيح عليه السلام يدعوا فيها الى السلام والانتاج والايثار , كما ان هناك احاديث كثيرة للرسول محمد وال بيته الائمة الاطهار صلوات الله عليهم يدعون الى السلام والانتاج والايثار منها حسن الظن , تشجيع العمل , الامر بالمعروف , اشاعة السلام , والابتعاد عن اكتساب الصور والمفاهيم التي تؤذي الى التفكير السلبي