There are a plethora of books and blogs encouraging us to not care what others think. I think it's a great idea. However, most of us have been raised from a very young age to notice, guess, intuit, and interpret what others are thinking and feeling, starting with our parents. Although what our parents were thinking and feeling was not always about us (well, often was not), as children we were given positive reinforcement for being a certain way when our parents were in a "bad mood" and negative reinforcement for being another way. We learned very quickly how to respond to our environment and please other people, like our teachers. I bet you are very good at it, in fact.
What we did not learn from a very young age is to notice, pay attention to, and be still with our own thoughts and feelings. We learned to respond to others feedback and largely ignore how we were feeling. Instead of noticing what our body and heart needed and wanted, we waited for a grade or feedback to tell us how we were doing. The idea to "not care what others think" is a guide and encouragement to, in essence, stop doing what you were taught, and start doing what you want, no matter the feedback. I love it! The challenge and question is, however, how do you do that?
One of the simplest ways to learn to not care what others think is to notice how you feel. What makes you feel less worried, more satisfied, or happy? By noticing how we feel, and changing our actions based on how we feel, we can start doing what makes us feel better. When we do things to make ourselves feel better (instead of doing things because someone else wants us to) we start down a path of not caring what others think. This all sounds like being selfish and possibly unkind, and for sure not what we were taught, so let me give you an example.
You have gone out drinking with your friends on Friday night after work for the past 5 years, barring a few exceptions (like being on vacation with your family). You like seeing your friends; it makes you happy. However, over the last year, you started noticing how much weight you've gained, so you joined a biking group that meets on Saturday morning. You really enjoy biking, and you want to stay involved in this group. You are making new friends, losing weight, and feeling more energetic. In fact, you notice that staying up late on Friday on a regular basis takes away your energy. You really do not want to let your friends down, but you also want to get sleep and bike on Saturday morning because it makes you feel good. What do you do?
Most people in this scenario would still go out with their friends, maybe try to leave early if no one gets too upset, and still get up on Saturday. The only problem is that you are tired and don't feel well. Maybe you miss a Saturday ride, because you need sleep, but you "can't" let your friends down on Friday night. You feel better drinking no alcohol or only a little, getting home early, getting sleep and getting up to bike, but you let your previous pattern and what your friends think or want drive your decisions.
This is where the idea, "stop caring what others think" comes into play. Doing what makes you feel better, happier, more energetic may let someone else down, and you did not learn how to do that. More importantly, you did not learn that you have permission to do so. However, making decisions that are in your best interest IS the path to your happiness.