I said what I did because I did it myself last month.
Somebody in a dually truck ran the stop sign in front of my house, ran over my dog, broke his back, paralyzed him from the waist down, so I had to take him to the vet in the middle of the night which cost alot of money, he couldn't relieve himself so he's peeing all over everything when somebody would try to move him, had to take a vacation day the next day, and ended up having to put him to sleep.
I buried him, and thought about hitting about 10 shots of whiskey, but decided to go running and biking instead. Before then I had only gotten up to 4 miles the week before. I got some new trail running shoes with alot of support, and was able to run 8 miles on the road just 2 days before. So, I went trail running and ended up going 13 miles. The only problem was that that was beyond what I was really capable of, the only thing that kept me going was pure adrenaline from being angry. So, when I got tired at about mile 8, I was running down a hill VERY sloppily, tripped, tried to catch myself, and stepped on a rock. It hurt like hell, but I was able to recover and keep going. After that, I rode the same trail on my mountain bike, still furious.
I got up the next day, and that little escapade cost me 3 weeks worth of not being able to run at all. I limped everywhere I walked for 3 weeks. When I started back, I couldn't even run a mile. For a week my muscles and knees were so sore that I couldn't do anything but watch movies and drink. I had made a total mess of things.
So... just be careful.