That first step towards your ultimate goal needs to be realistic in order to be achievable. Start small. You’ll get there.
It’s perfectly okay if the only step you know right now is the one right in front of you.
Do you already have it in your mind you’ll fail at something new? Why not try it just to either confirm your suspicion, or surprise yourself and excel? But you won’t know for sure unless you actually try it.
There’s so much in life you will never be able to plan for, so keep making new plans as necessary.