When we're enthusiastically doing something, involved in an activity that is aligned with our needs and goals, of course it's easy to be positive. When everything goes badly wrong its hard not to be negative. So one cannot necessarily be classified as a positive/creative or negative/destructive person, there are all the in-between states, and in one area of our life we may be enthusiastic whilst in another, we may be deeply depressed. And this can vary over time. Nevertheless there tends to be a mean, a state that we are typically in, and that we identity with - an identity that others at least can clearly recognize.
One reason for feeling down is when we don't feel we are getting love or respect from others, or we don't feel cared for or even cared less about. Belonging is a basic need for all people.
The other side of the coin is when we don't really love ourselves, when we are lacking integrity, not feeling whole. This occurs when we are not being true to our own values and goals. When we're doing what we don't really want to do, or not doing what we really do want to do. Or when we've made mistakes and try to disown the action, as if it never happened or was another's responsibility, instead of taking the positive, creative approach, which is to learn from the mistake, to understand and empathise with why it was done and why it would be better to act differently next time.
Knowing who you are, self-realization, is another basic human need. It's about making the most of your life. Some of the things that make living worthwhile are creatively envisioning and achieving goals, having fun through involvement and interaction, beauty of all kinds, humor and unpredictability, being of service to others, to love and be loved, and to discover truth. Life is, to a significant degree, for learning - so when things don't go right, when we do wrong, make mistakes, and when we do things right as well - these are all learning opportunities.
Learning can be positive when an experience has been properly digested, so new skills, coping and mastery are developed - or learning can be negative when the experience is perhaps overwhelming and has not been integrated, and so future avoidance patterns become imprinted - what could be termed 'unskills'. So long as you eventually learn from it in a positive way, no experience is wasted.