You sound a very sensible person as you are asking the question, showing you are putting the dogs needs before your own. Taking on a 7 year old is very different to taking on a puppy.
In 2021 I lost my two heart dogs and I didn't have a purpose to get up in the morning. I have had two spaniels together for a long time and I was lost without them. I live alone and I was worried about taking on another dog as I have had 3 slipped discs which has left me with spinal problems.I talked to one of my daughters and it was agreed she would have the dog if anything happened to me. I then went ahead and got puppy Maisie ( it was during Covid and rescues were practically
impossible to obtain ). I then got Ned nearly 3 years ago but as before I asked my daughter. I have made provisions for them in my will so that my daughter will be able to look after them financially.
Having the dogs means I have to go out and walk them and I have found the exercise actually helps my mobility and strength.
None of us know what will happen in life. Being young doesnt t come with the guarantee that you will have a long healthy life.
Making provisions for your dogs future will provide you with peace of mind too
There are lots of older dogs looking for a loving home and would enjoy pottering around in your garden. Maybe also look for an older dog who is not that active or has health problems. Just that my previous working cockers were as fit at 7 as they were at 2!

Did not start to slow down until they were about 12.
if you feel up to it - go for it.