Well done Derbyshirelady! If you're feeling a bit achy today, the best thing really is to get moving again, even if just a walk to get the blood flowing to all those tired muscles.
I'm definitely fitter in my 40s than I was in my 20s, and there's definitely room for me to do more, but life needs to be balanced! I started my fitness 'journey' about 4 years ago as I slid towards turning 40. I started to see a PT to give me a kickstart (and a kicking), and I haven't looked back. Once exercising weekly became my normal, I started adding more in. I trained for a 10k run in my 40th year, and now as I edge towards 44, I get tetchy if I'm not doing something. So I still see the same PT, fortnightly now. I go to a circuits class weekly, yoga weekly, and then might go for a run (4-5k, running's not really my thing), or do a Fitness Blender session at home. We have a treadmill at home, and DH has just bought a spinning bike, so even during the long winter months, we can still exercise at home, no excuses. If I do no 'proper' exercise one day, I'll definitely go for a walk, even if it's on the treadmill.
This has been a long process, I've never been someone who naturally enjoys exercise (I do now to a degree, although my natural instinct is to stay nice and warm under the duvet!), but you've made the first step to making positive changes to your life. Good luck!
I also have an Apple Watch which really helps motivate me too, if that's an option. Mine is tied into my health insurance, so the more I move, the better benefits I get (free cinema ticket a week, free Starbucks coffee a week, free Apple Watch, free Amazon Prime, reduced BA flights etc etc etc).