Exhaustion: stroke or old age? - NOT amateur radio

Later this year I turn 70. In 2013 I had a stroke. At the moment 15 minutes of physical work leaves me totally drained. I am unsure if this is as a result of my stroke or just me getting older. Either way, it is no fun. In many ways I feel so much older than, say, 5 years ago. I try to remain positive, but it is hard.