Realise you perceive nothing directly. You perceive only your interpretation of it. Therefore nothing can directly make you feel good or bad. Only your interpretation can do that. Part of mindfulness is to realise when your interpretation is not serving you, perceive it for what it is – only an interpretation you have created, then go on to change it. For if your feelings and thoughts were a directly caused by a thing outside of you, you would never be able be able to change them unless the thing itself changed first. Yet we all change our minds about everything, drifting from one interpretation to another, believing them to be objectively true and unchangeable. Not realising we are the creators of each one of them: we create by accident and play victim to the horror stories we write for ourselves.
This is what the teaching of ‘you create your own reality’ truly means. As you think, so you shall be. As you interpret, so you shall react and make it real for yourself.