Being stuck inside can be torture. Not getting exercise can be depilitating. Therefore, it is ideal to be able to exercise outside every single day. Having said that, there are a number of factors which may interfere with fulfilling this basic human need and weather might be the thing which tops the list. It can be excessively hot, cold, wet, or windy, making going outside difficult. Of course, it is possible to exercise inside, but not everyone has access to a large and spacious gymnasium. Some people don't mind using treadmills, but those are suboptimal compared to actually walking, jogging, or running outside. So, although there are substitutes for actually exercising outside, there is nothing quite as good as the real thing.