>be 25 yo male, 215lb >want to get in shape >walk 30

You're so out of shape your body thinks it's dying from some moderate exercise.

If you were a total couch potato, it's possible that your body has disadapted to stress to THAT extent. It's going to be ok next time, or the time after that. Just be sure to take a good rest before that

>>42792794
>>42792778
This.
You're just horribly out of shape and the stress from exercise and more then likely the stress from life has hit you like a brick.

If you don't want to be down and out for days at a time then start with a basic calisthenics thing along with a 30 minute daily walk.

>>42792816
most of my exercises were little band exercises (standing hip abduction, basically rows with a band tied into a door) or small stuff like 5lb rear delt flies... heaviest thing i did was do a farmer walk with 25lb in each hand for a few min. hard to measure resistance with a band so i did most of these "close to" failure... not sure if it was a good idea

>>42792896
Never a good idea to take on sub-maximum loads right away. It's dangerous and it's not your maximum. Take it slow, in a couple of training sessions you're going to reach you max potential and start progressing. The feeling of dying in the morning will be changed to jumping out of bed with the force of 1000 suns.
Good luck