I think onemoretime put it quite eloquently.
Regarding my own situation.
I am seeing doctors regarding my sleep problems, and there are some health issues that could definitely be the cause, but so far that has yet to be resolved. Till, it is resolved, it is a limitation that I need to account for.
I aim to make my "dabbling" in fields a way to synthesize new breakthroughs. I am explicitly picking an interdisciplinary field that can use my prior skills...I will have a very unique perspective entering the field.