The study linked below reports on an interesting kind of litmus test for heart health in middle aged men: if you can do forty pushups, you’re much less likely to have heart problems over the next ten years.
The usual warnings apply about correlation not implying causation. It’s possible that men who can do forty pushups typically embrace other healthy living habits or enjoy some genetic advantage. Thus, a sudden intense micro-focus on pushups may not be the answer.
Nevertheless, the long-term physical benefits of strength training are well established. I found Hacking Exercise for Health to be a very informative and motivating short course on this topic.
Men Who Can Do More Than 40 Push-Ups Far Less Likely To Develop Heart Disease