Any exercise you do is good for health.
If you've got specific goals then you need to regularly review what you do. Play with the number of reps and weight as exercises feel easier. I find gyms dull and hard for motivation so a group setting works better for me for weights. Running, I find more flexible and easy for goal setting so can do that solo.
Exercising in your 40s is an essential stage of keeping mobile, keeping strength and maintaining muscle and bone density into later adulthood. Good muscle mass does help maintain metabolic weight too. Exercise helps maintain weight, but is a small part in reducing it.
I don't diet. But sometimes I have to focus on nutrition and on adjusting habits. There is a slight distinction. I don't have to change everything in one go. That means I don't "cheat" or "fail". It's about trying to remember the role of water and nutrients in my lifestyle, and aiming for better not perfect.
Water and good hydration is essential to break down fat. Reduce sweet drinks be it sugar/ juice/ sweetners. Your body will metabolise sugars (inc in juice) first. Sugar spikes and crashes stimulate appetite within a few hours. Artificial sweetners can replicate those effects on the body and increase cravings.
Use naturally low calorie vegetables and some fruit to fill up on fibre. Then add proteins and healthy (less processed fats). I'm not anti-carb, but it is easy to consume too much. Carbs have a prominent place on the food pyramid because they were useful and cheap for filling up the post-war population when food was less abundant. If you have plenty of fibre, protein and fat on your plate, you don't need so many carbs.
Don't ban things, but work out how to fit them into your life in practical portions, e.g. save for the weekend.
Eat food as close to its natural state as possible. Reduce processing- the more recognisable the ingedients, the better.
Cooking doesn't have to take hours. If time is limited, frozen veg/ stirfries are a great time saver and often frozen in a fresher state than the food in the "fresh" section. Avoid artificually processed "low fat", the fat will sate you better and you eat less of it long run.
You don't have to change everything in one go and it's easier to tweak one habit at a time and it also makes it less likely that all habits will collapse at once when life gets in the way because special occasions, illness, busy phases etc are all inevitable.
Being small makes it hard going because you need less energy to survive than average, but you still want to eat "normally" and enjoy food. It takes a lot of patience.