At this age, it's a bit more difficult to become fit after having led an inactive lifestyle, and there are a couple of reasons for this.
The first reason is fatigue. It doesn't take as long to get winded, and you don't recover your breath as quickly. By the same token, once a muscle becomes fatigued, it stays that way for quite a bit longer than it used to. In fact, fatigue also builds up noticeably over time. If I exercise hard for several days, I may well need to rest for several days afterwards... So progress just isn't as fast as it once was. I'm OK with it - that's just the nature of aging.
The second reason it's difficult to regain fitness is injuries and pain. Age has a way of introducing new pain and amplifying old pain. I am enormously blessed to have a (mostly) pain-free back. My pain lies in the small joints - elbows, knees, shoulders and wrists. I think that most people can work through minor pain, although it makes exercising unpleasant. Really harsh pain can keep you from performing lifting exercises with proper form - which can also lead to injury. And by injury, I mean torn or detached ligaments, muscle tears, and bone injuries. The potential for injury, combined with current pain, has made me *much* more wary of using heavy weights.
Here on the far side of 50, I'm pretty sure that any kind of injury would be long-lasting and difficult to recover from. It would also be likely to leave me in moderate pain for the rest of my life. Who needs that? So I'm staying clear of the really heavy stuff. However...
Your muscles have to be stressed and overloaded in order for them to decide it's time to add new muscle fibers. The best way to stress and overload muscles for growth is to lift heavy weights - preferably without injuring yourself. So now you have conflicting needs right there: You need to abuse your muscles with heavy weight to make them grow, but that same heavy weight makes an injury more likely.
Eventually, heavy weights or not, you will manage to grow your muscles. The more active muscle tissue you have allows your body to burn more calories, thereby accelerating body fat loss. When combined with a proper diet, you *should* be able to put on muscle, while also burning off fat. This is a difficult balancing process however, and you are not guaranteed to get this exactly right. Eating in a calorie deficit can cause muscle loss, so it is important to keep protein consumption high and consistent through the day.
It's also good to get a little cardiovascular exercise every couple of days. I don't enjoy cardio at all, and it doesn't contribute toward my goal of being more muscular. However it does improve lung and heart capacity, which indirectly helps in that goal. BTW if you think lifting weights doesn't improve cardio fitness, come join me on leg day sometime. Better yet, try doing a set of 10 Olympic movements. That will take your breath away.
Below: Mah ghetto gym. None of the weight sets match, and most are too cheap to have grips. The left rack holds Olympic weights and the right rack holds standard weights. The bench and bar sat out in the weather for years, and it shows. You could probably put this entire rig together from Craigslist sales for well under $300.
Regarding diet, I am a huge fan of the Ketogenic diet, like the one Dr. Atkins made famous. I'm not partial to any specific ketogenic diet plan (there are many), but I try to keep my carbohydrates very low, proteins high and fats moderate. Alas, this diet precludes drinking beer :( I suppose most healthy diets do preclude drinking beer.
The ketogenic diet is an excellent body fat burner, because it reduces blood sugar levels. The reduced blood sugar forces the liver to metabolize fat. The metabolization of fat is the body's response to low blood sugar, propping the blood sugar up by breaking down triglycerides stored in fat. The ketogenic diet also releases ketones, which are volatile and stinky like acetone. They are released via breath, sweat, and used as fuel in the brain. You don't smell good on a Ketogenic diet.
There is one nasty down-side of a Ketogenic diet when combined with heavy anaerobic exercise like lifting. Due to lack of dietary carbohydrates, your muscles don't have much stored energy in the form of glycogen to work with. As a result, you don't have the power to make bigger lifts. You feel weak because your muscles run out of glycogen fuel very quickly. The Keto diet and lifting makes for a lousy-feeling combination, even if it's highly effective for simultaneous fat burning and muscle building.
I tend to bounce in and out of ketosis while doing this, because eating more protein tends to knock you out of ketosis. However you need to boost the intake of protein quite a bit to add muscle. I'm really looking forward to getting my body fat low enough to start boosting my carbohydrates, feeling better and lifting a little harder. I don't want to mess with carbs now, because I am trying to lose fat, not gain it. Excess carbs become fat - as do excess proteins, although to a much lesser degree.
So... the reason I'm finally getting serious about fitness again?
I have a couple of reasons for that, too. One reason is my family. They are all that really matter to me. I need to stay healthy in order to continue to provide for them. My job isn't terribly physical, but if I have a medical issue, I won't be able to work. If the medical issue was preventable, then the loss of income will be due to my own negligence.
Another reason that I want to improve and maintain my health is to stay out of the clutches of the insurance/healthcare/pharma industries for as long as humanly possible.
$300 for some rusty iron and a workout bench seems pretty cheap compared to the chart below...
EDIT: I guess it was around this time frame. After reading that article I now understand that the US is being medicated not for illness, but for ill-defined non life-threatening "conditions" (like Low-T), which may just be part and parcel of a normal life. Would you also care for some lethal Vioxx to go along with all your other unnecessary prescriptions?
So there you go. Eat right and exercise. If you do that, you can skip the endless medications with awful side effects, blood testing, and fighting with your insurance company. It's your family's wealth, and your valuable time and health going down the drain....
Try to be the figures below, and not stuck living endlessly with the crap above :)
p.s. Avoid sugar. I'm not sure it's any better for you than smoking.