All of us, when we truly challenge ourselves, go through some degree of feeling like a fraud. Those in Leadership positions are no different. Even when you have been in that position for many years, it still comes creeping in. Some of you may be reading this thinking, psssh Renata, I don't ever feel like I am "faking it". And I know this may go against probably every single article written out there about the Impostor Syndrome, but I would have to say that if you aren't questioning yourself to some degree then you probably aren't challenging yourself to grow.
I think there is a fine line between questioning yourself and learning how to deal with it and being in full-blown Impostor mode. I believe it's good to go for the sink or swim positions as long as you are in the right headspace and are firmly grounded in what you do well and where your gaps lie. If you know your gaps, then you know where you need to grow and you have ultimate control in how you become an excellent leader.
If you want to become a new Leader, but are being held back because you lack the "right experiences", I would start taking personal inventory. List out what you feel your skills are and where you have gaps. Then for each, you should expand a bit. How will the areas you do well in benefit the teams you wish to lead? Layout your gaps and how you can fill those in a timely manner. (coaching, mentoring, courses, books?) I would present those the next time you have an opportunity to move up. Being open about your growth should get you closer to that leadership role.
For those of you who feel like you have this Leadership thing all figured out, I'd recommend you take an honest inventory of what you do well and what areas you are ignoring. I say ignoring because if you feel like you are the perfect leader, then you are either ignoring something or you feel like a skill isn't important. Review the many skills it takes to be an effective Leader. Ask your team, ask your co-workers. If no one will tell you where you need to make improvements, then I can tell you it's in the arena of trust. If you are honest with yourself, you too will find the gaps that need work and can face your doubts head-on.
If you are in full impostor mode, search the internet for ways of dealing with it. There's a lot of articles out there, and surely there's one that will resonate with you.
Personally, I believe challenging yourself is a good thing as long as you know what you are capable of. Not knowing everything is perfectly fine as long as you have a plan and don't let it turn into an overwhelming impostor syndrome situation. If you aren't challenging yourself...why not??