Welcome to the group. Good on you for starting to plan already to get/keep fit after surgery etc. Be ready though for things to change though, because one thing you can count on in the cancer treatment is that just when you think you know what is coming next, it changes.It really is a roller coaster ride.
So don't take it to heart if that happens or get frustrated or upset, just remember leave a little room for flexibility for plans to change, and to be ready for it. You may for instance find yourself fatigued during radiotherapy. Even so, if you push yourself you should be able to walk at least, and get a good halfhour to an hour each day.
And on the other hand, don't underestimate how much even a small lumpectomy hurts when you stretch the tissue around it- after a small, wide-excision biopsy my very fit daughter Miriam was walking with me an hour a day for about 3 weeks before she was able to do much exercise of any sort that stretched the wound/scar site.
I gather they have explained to you that with a lumpectomy you will also need radiotherapy and you have prepared for that.. Have they also decided to remove your sentinel lymph node, with a plan to remove several or even all the lymph nodes in your armpit if it has cancer in it?
Have you had a core or wide-excision biopsy yet to identify what Grade (ie how aggressive and fast growing the tumor is, and if it is Estrogen Receptive Positive or Neg, or Progesterone Receptor Positive or Neg, and/or HER2+ Receptor Positive or Neg?
(Many people don't have those sorts of biopsy, so don't know this info at the pre-surgery stage.I had Fine Needle Aspiration biopsy that got enough cells to say it was malignant, but nothing more).
So be prepared for the fact that the surgeon and oncologist etc probably won't have enough information until after surgery and after the pathologist has stained and studied the tumor for a couple of weeks before they will know whether or not you will also need:
a) two to four months of chemotherapy and/or
b)a year of targetted therapy and/or
c)five years or more of hormone therapy.
d) more surgery
The tumor tissue and sentinel and other node tissue will give them these answers
At the moment you have to live with possibilities and probabilities, be learning an enormous amount of new information, and at the same time try to live with a rather scary life-threatening reality.
You are doing well!
best wishes
Jessica