There are fine lines between encouragement, challenging someone to improve and criticizing them. Aside from when you are raising children (I think there is a different dynamic) most adults seem to err on the side of caution.
People tend not criticise. They avoid confrontation. Encouragement is always 'positive', and critcism is required to be 'constructive' - whatever that means. If you are serious about personal development, growth and your own success, I have the following advice for you:
Embrace criticism, disagreements and confrontation. More than that, actively seek it out.
Deal with it by recognising that the 'criticism' is about the process and not about the person. Even when someone criticises you for being arrogant (for example) - it may seem at first glance that they are being critical of the person, but they really are simply articulating how they perceive your impact on themselves or possibly other people. It isn't a criticism of who you are.
Even when it sounds like it or feels like it (at first cut) - take a pause to consider. The person doing the criticizing may just not have the skill to de-personalise the observation - and you need to simply re-frame that observation in your own terms. Then consider it objectively (unemotionally) and decide what to do about it.
You cannot live you life by avoiding criticism or moderating your actions by the light of every disagreement. You need to be stronger than that. Your self-identity should be strong enough to consider every criticism, evaluate what it means in the context of your own goals and objectives, and formulating an appropriate response.
And often the response is - or should be: 'mmmmh, interesting - I understand where they are coming from, but I am going to continue down this path.' If the observation clarifies why you may be experienceing certain obstacles, then you may moderate your behaviour to facilitate achievement of your own goals.
Criticism is not like a rock in the river that you should 'flow around'.
A better analogy would be that criticism is like a chisel that can shape your behaviour. And sometimes it is or should be too blunt to make a difference.