Deep Vein Thrombosis, what is it and what can it do to you?
One thing for sure it flat out doesn't matter what physical shape your in, prolonged sitting can and will cause this silent and most deadly situation. Individuals in excellent physical health have been known to step off International flights after sitting for 10 to 14+ hours and collapse within minutes departing the aircraft. Same can happen after sitting in a car/truck, boat or even a tree stand.
I strongly recommend to read the following link, it just might save you or someone you are with!