I did not start on Letrozole until 2 1/2 years after my initial treatment. I was on Tamoxifen until I had my ovaries removed and switched to Letrozole. I found I was fatigued for a good 12 months or more after my chemo and radio treatment. Then I came good and did not notice a return of fatigue when I switched to Letrozole 2 years ago.
However, I will say that I do not handle stress very easily anymore. That leaves me feeling overwhelmed and sort of fatigued really quickly. Like the others have said exercise helps the energy levels. I think just being diagnosed with cancer gives you a type of Trauma stress reaction which can have a big effect on your energy levels, let alone what physical effects various treatment also have on us!
My family know that I need my walk every morning or life is not good!
:)