It is so easy to be overly optimistic, or even overly pessimistic if you do not have a good understanding of the realities that you are facing in your career change. Write down your true skills and honestly evaluate if your skills and experience are a good match for the work you are seeking and for any job advertisement which you are considering. If there's a good match then go for it! If there isn't, there is little point in applying for that job. You will be wasting your time and that of the person whose task is to review your application.
Have clear and precise goals, enhanced by some optimism and you will find yourself attracting success. Clarity of your goals is essential because if you know what you want, you will recognise it if the job is advertised or if you hear about the opportunity through your network. However, if you can't really explain to someone the sort of work that you ideally want to be doing then you probably aren't ready to start making your career change yet.
Do you have a deep understanding of the current labour market in your area of expertise? it is important to do some research and find out about salaries, conditions and current job descriptions in your industry to ensure you are up to date with what is expected of you. So often people apply for jobs and have their blinkers on to the reality of the labour market, then they wonder why they have difficulty getting work. The old dating adage "It's not you, it's me" so often applies to job applications. When people are unsuccessful in their applications it is easy to internalize it and perceive the rejection as failure. Yet usually it is just that they were not what the employer wanted, and if they'd read the advertisement properly they'd have realised that!
With determination and talent, complemented by strong employability skills, you can reach your ambitions. However, you need to be realistic and maintain your optimism, knowing you have done all you can do to improve your chances of a successful career change. Arm yourself awareness of the job market in your indsutry and deep self-knowledge and you will achieve your career dreams.