Well done, Whiff . You are doing the right things to keep healthy and yes, staying that weight or a bit less is the long-term, lifelong thing.
I was like you, always overweight, size 16-18 and yoyoing and struggling from about age 10. I got to a pound under 19 stones and at age 60 I could hardly walk as have arthritis. I went o Slimming world and lost 3 stones. thought I could do it alone from then on and stopped going and began to gain. I then went to Weightwatchers and lost a further 5.5 stones.
This took about 4 years though. Slower stays off. I've been WW gold member since 2009 and am able to walk again. I swim daily and walk on a treadmill and do tai chi. Getting 2 dogs helped a lot as they have to walk, rain or shine, hot or cold. But it means I have had to change my pattern of eating.
I count the WW points as I love eating and still have days when I lose the plot and can gain 3 lbs in a day! That 3 lbs takes several weeks to lose again. I weigh in weekly at WW as the check there means I can't fool myself. And the advice and encouragement and tips on what is filling but healthy and less fattening are so helpful.
I was around 64 when I got down to a healthy weight. There are ladies at my meeting who are older and bigger and find the advice helps them. This has been an advert for slimming groups
I have a group of online friends too and we weigh weekly and chat about health and weight.