I have your answer!
Use the amazing new science of exercising in a specific heartrate zone - neither more nor less - for specific results.
For example, http://www.thewalkingsite.com/thr.html
First calculate your MHR (max heart rate) as described.
Next, buy the cheapest heartrate monitor you can buy - order it now. (They only cost a few dollars. They are all exactly the same, so it is utterly pointless buying an expensive one.)
Next, you should exercise at 70% of your MHR. Allow plus or minus say 3 or 4 each way. (So for me, it's 120. So, I have to keep it between 116 and 124, for example.)
Next, get yourself up to one hour a day but only at exactly that 70% heartrate - no faster (or slower) heartrate.
You will find your improvement is incredibly fast.
At first I was only able to jog 30 minutes a day AND I had to break that up in to three groups of ten with a rest between. Again, very strictly keeping to my 70% rate at all times. (Do not do less than 10 minutes "sections" - force yourself to keep it up for 10 mins.)
Now as little as an incredible two months later, I can very easily jog/run at that 70% level, for two HOURS with no problem, at any time, almost any day. (I run for an hour basically everyday currently.) Plus I'm an old fart. If you carefully and aggressively stick to the 70% level (resist the temptation to go harder) your improvement will be astounding. And you must do at least 30 minutes a day, starting today.
Tip: if presently you find it hard to reach that 70% heartrate, while jogging: try this: find a hill and just "walk quickly" up the hill. (If it's a steep hill, just climb slowly up the hill.) Watch your heartrate monitor carefully and get your heartrate at exactly that magic 70% level. Of course you could I guess use any of the popular machines, treadmills, etc.
I only learned about this 70% business here on this web site, with thanks to BackInShapeBuddy and the rest. So I hope it helps other readers.
Further thinking: your diet has to be critical. Have you read Protein Power Lifeplan by the Drs Eades. It could change your life - of course, every diet science has people who do and don't "believe" in it. However it's dead easy to try or say 3 weeks, and the change in your running energy for very many people is astounding. It's by no means a "painful" dietary regime, you eat as much as you can stuff in your face, so it's painless to try and if it works for you, you have a new lease on life.