Another difference between Crossfit and cross-training is that Crossfit is a compact package of intense activities. For older people, it can be too extreme to overload their body with that level of intensity.  On the other hand, cross-training is more flexible and allows you to select different modes, intensities, and variations based on needs, age, and fitness level. For example, a combination of swimming and climbing can be a perfect training regimen with unique mental and physical benefits.