I used to go to the gym until they dropped my insurance. Now I go to the Commission on Ageing (COA) and do their exercise classes for free. I also have made new friends and so have increased my support system. Also, walking still is the best exercise you can do at a low cost. Start by just walking a short distance and increase it weekly. You might also meet neighbors by doing this. There is also Thai Chi and Yoga which I attend again at my COA. I don't know which country you live in but check around you might find some low to no cost ways to exercise.

Walking. Aim to increase a little at a time distance walked. Tae chi is good for stretching. Is slow and you can get you tube videos that specialise in tae chi for fibro. Finally exercising in water. Warmth and body support makes it easier.x

Swimming is out due to a back injury.I have been advised not to use my legs swimming ( gave you ever tried swimming without using your legs??). I have dyspraxia and so have balance problems. Stamina is next to zero these days.
No I am not just finding reasons to not do anything. But I really do have the 'cards stacked against me'.
This is the problem
I tried just doing some gentle exercises using a couple of cans. Made me ill for two days and had to double up on morphine.
I made (slowly ) a salad for tea for my carer and myself today ( she has picked up my chest infecction and is feeling rough. So I wanted to help). Took me two hours to prepare and I was worn out after it.
This is the problem. I still feel like I should be able to play rugby/go for a walk/do diy/gave fun.
But i can't do any at all. Washing myself (with help) and dressing ( with help) wears me out.

Steele,
Thank you for you reply. I suspect you greatly over estimate my capabilities. I have multiple conditions including adrenal insufficiency.only one adrenal gland and a VERY 'deaf' body.
On my absolutely best day I could walk perhaps 200yds. Normally 50ft.
A bad day. Zero.
I am unlikely to build up stamina as I do not produce the chemicals to properly drive my body.
I am not giving up but this is where I feel I need someone who fully understands my limitations to guide me. Mlat the mo, i still have a bad chest from a chest infection, my adthma is very bad and not controlled. I have had several 'dips' in my functioning ( loosing control of an arm for two hours. Suddenly being very clumsy. More then usual.
Sudden loss of memory ( part way around a supermarket forgetting what i am doing let alone what i went for!).

For us I believe walking is the best exercise available.
Many have bad joints and running or any high impact exercise doesn't help.
You get very little benefit for running over walking anyway.
I started out walking just a little bit then a bit more then added ankle weights and now up to 3 miles some days and working towards that amount EVERY day.
Cut calories and add protein and I lost 25 lbs in two months.

It is not as much 'how' much you do as how often and consistent you are in doing it.
After you build up whatever you do, do it for at least 20 min at a stretch.
As a former aerobics instructor I can tell you that is what will cut the weight and improve your cardiovascular system and lead you to better health.