How to train for a relay in a week and a half

It is not recommended. In my mind I am still at the same fitness level I was a month and a half ago just like in my mind I am still 21. Sadly I am not really fit at all and I am soon to be 31...(ahhh what, that shit snuck up on me). In a nutshell I am feeling winded and ....mature. I have noticed as I have gotten older I don't get in shape as quickly or stay in shape as long or recover from deciding that lifting weights is a "good idea" quickly. And since I have had about zero time to get back in shape for the Wild West Relay I am not really sure how well that is going to go. On the one hand I am super well rested. Injury free. And a bit stronger due to body weight training and Pilates. I feel ready to go. On the other hand this race is at high elevation and I am way under trained in the running department So my general approach to the last few days and the next coming days until the relay are to run (either a HIIT on the treadmill or and easy outside run) abou...