Chuckster, I started treatment January a year ago. I am a 67 yo guy. About 6 weeks in, I had bad muscle pain that woke me up from my sleep. I had a great response and my Oncologist lowered me to 50 mg which solved most of the problems. I agree with other posters, 100 mg is too strong. As long as your response is good, you are better served to be at a lower dosage. I am currently as 40 mg. I firmly believe that after 30 days at 100 that you can and should have a dose reduction. The pills come in 70 and 80 mg strength as well but I am happy at taking two tiny 20 mg pills.
At first, there is the shock that you have cancer that would have killed you 25 years ago. Now I realize that something else will eventually kill me. I have to be muted in my feeling about being lucky in the Oncology waiting room as most of the others don't share our luck. Make sure that you are religious about taking your pills each day. I have a 9 PM reminder on my telephone that just says "Spry". It will take a while to not be freaked out about a cancer diagnosis - keep moving and enjoy your life.
One more thing, I was getting tired even before my diagnosis. If a little bit of fatigue is your worse side effect, it sure beats the alternative.