A mind like a sieve

How did I ever do relatively well at school and then go on to get professional qualifications? My mind is like a sieve. Well it seems like it as I struggle to revise things that I once knew. Perhaps I should not have signed up again for a class starting next week. My good intentions to continue with the studying during the four months since the last class came to nothing. I have paid for the next series and bought the books so can’t give up now but will I be the class dunce?