Physical performance and lifespan
There are countless studies on this topic. All of them unanimously show that physical performance clearly correlates with lifespan! If we had any drug in medicine that showed even a halving of the risk of death when taken, practically everyone would take it. In medicine, we are usually proud when taking a drug lowers a surrogate parameter – e.g. cholesterol. If the risk of death also decreases significantly – even if only by a few percent – then we recommend taking it.
Fitness and service life
As an example of studies on the relationship between fitness and lifespan, I would like to introduce you to the results of Laukkanen et al. who were able to show many years ago that the risk of dying is clearly dependent on maximum physical fitness. 2682 men between the ages of 42 and 61 were included in the study. The observation period was 5 years. Men who had less than 7.9 METs maximum physical performance had a four times !!!! higher risk of dying during the observation period than those who had a maximum physical capacity of > 10.6 METs.
In this study, maximum physical performance was expressed as metabolic equivalent (MET). Here, 1 MET = 3.5 ml oxygen consumption / kg / min. If this is converted into calorie consumption, assuming a caloric equivalent of 4.8 Kcal / l O2 consumption, this results in a value of 1 Kcal / kg / h, which practically corresponds to the basal metabolic rate.
For a better assessment of the data: A maximum physical performance of 7.9 METs corresponds to a maximum oxygen consumption of 27.7 ml O2 / kg / min; 10.6 METs corresponds to a VO2maxof 37.1 ml O2 / kg / min. Translated into practice, a maximum physical performance of 7.9 METs means that the person in question is able to reach a running speed of 7.9 km/h for at least 1 – 2 minutes. In this study, 10.6 METs therefore means a maximum short-term running speed of 10.6 km/h
I would like to refer you to the chapter “Assessment of physical performance” for the possibilities of conversion. (follows)
Fitness and risk factors
In a large study, Myers et al investigated the influence of physical performance, fitness, on lifespan. They were able to show 
that even in the presence of risk factors – such as high blood pressure, chronic obstructive pulmonary disease (COPD), diabetes, smoking, obesity (BMI>30) or high cholesterol – physical fitness has a very significant influence on the relative risk of dying!
Men whose maximum oxygen uptake was measured at < 5 MET, i.e. who could not even move at 5 km/h, had about twice the risk of dying compared to those who were able to perform more than 8 MET maximum (roughly more than 8 km/h maximum speed).