Indulging in Self-Doubt

I believe I have an opportunity to become a marketing director at a company, but I keep spiraling into self-doubt, telling myself that I don’t have enough experience, that I’ll get hired and then let the company down, etc. On the other hand, I know I’m capable of learning and teaching myself when I encounter gaps in my skills. How do I keep myself in a positive mindset and not jumping back into doubt and fear of failure?