Don't burn out! Ask for help and guidance when needed, and take care of your mental and physical health (get a hobby, go out with friends, go to the gym, etc.)
I've seen brilliant people burn out and end up leaving/missing out growth opportunities because of it. Now that I manage people, it is my biggest area of focus because many times the best employees are the most at risk. They keep getting praise and asked to be involved in more and more and it becomes hard to say 'no' to new projects, responsibilities, etc... Until it is to much.
When it happens everyone looses, your boss, your team, the company, and especially you.
This sounds like a conversation for you and your manager. I've had a few with my team that have resulted in different solutions for different people.
With one we established a monthly 1h call for her to explain where she is stuck, what she has tried, and we brainstorm how to get through it. This is separate from our usual weekly check-ins and focuses on issues related specifically to complexity and ambiguity.
With another, he created a list of what she thinks needs to happen and puts together ideas on how to get through it. I review it and then give him feedback. He liked this as over time he built confidence on his ideas as my feedback more often than not was "exactly what I would try, go for it".
Finally, sometimes is about reducing the work load on that team member until they get a good foothold and slowly start adding more.
Shot answer, no one solution or easy path, but communication with your manager and hopefully a good manager is your besy bet.