I've been run through the mill in recent years and ended up even worse out of shape than usual.   I've been in  lymphoma remission about a year now.  However, the aftermath of chemo has left me in much worse physical condition than I hoped.  I've honestly not focused on my fitness until now for family emergency reasons but now need a basic starter program for a 55+ year old that has been knocked down physically and has put on too way too much weight (and has psoriatic arthritis) to allow for running.  A gym membership is out because cancer has put me years behind financially and I have a daughter in college.  On the plus side, I've got really good access to  the outdoors for walking and can get a limited amount of free weights.

Initial Goals:
1.  Build hand/wrist strength back.
2.  Improve arm strength.
3.  Improve range of motion for knees and shoulders.
4.  Build walking/standing endurance.

I'm not super focused on weight loss as the principle goal at first.  I'm hoping to get that as a byproduct but do plan on a generally better diet.

Any suggestions?  Example, walk each week for X and do the following Y exercises for Z times a week.

As a four-time cancer survivor that's been radiated and poisoned....

I play the drums semiprofessionally so that was part of my physical/mental rehab. Probably not an option for you, but if you used to play a guitar or something in the past, consider taking it up again. That will work your brain and your fingers/hands/arms. Don't overlook the chemo mental fog.

I also walked on a treadmill and walked the dog. That was almost an everyday occurrence for a while and wasn't particularly long or far. I tended to wear wrist weights or hold small weights while on the treadmill, but not always. The only other thing I did was some free weights of 5/10/20 lbs and just did 10-20 reps of whatever and then a 30-60 second rest, repeat until tired (but not hurting).

If you haven't examined your diet yet for unnecessary carbs/sugars, do it.

In the end, you can do almost anything regularly for physical activity and you'll be far ahead of doing nothing. Don't over think it.