I too have recently been diagnosed with Advanced Prostrate cancer spread throughout my bones and lymph modes. On hormone therapy and enzalutamide treatment however PSA levels last checked plateaued in high three hundreds. Its very hard to stay positive your cancer team are there for you both and will be able to put you in touch with a professional or just someone you can talk to if you are comfortable with that. Personally just try to take each day one at a time good days and not so good try setting myself small achievable goals.