I waited for Kobi to be almost a year before finally running with him. A few years ago a neighbor got the sweetest golden retriever puppy, the poor thing never made it to a year old because the daughter would take him on three hour jogs with her almost daily. Because he was growing his hips got destroyed, completely locking up to point where he could no longer move. So that was the image that came to my mind when I wanted to run with him and I made sure I waited for him to finish growing and start things slowly.
Be patient! If you have a reactive dog, running is exciting and new, give them time to get into a groove. Don't ignore them, follow their body language.
Give them breaks. This is good for me to catch my breath since I'm still not great at running, but if Kobi has just passed something he would normally react at I'll let him "go sniff" once we've passed it. This gives him a second to reset his brain.
Be observant. It' actually easy to just zone out while your running and concentrate on your breathing, great if there are no people out when you're running, no so good if you run at a busy time of day like when kids are heading to school. I have to be vigilant when running, constantly assessing, "can we just run right by this person?" or "do I need to walk and treat as we pass this person?". Don't force them into situations that may cause a reaction.
Bring Treats! I run with a fanny pack, I know, lame. But now with the warmer weather I don't have a jacket with lots of pockets and I still need to bring my phone, keys, treats and poop bags. I bring high value treats like liver when we run because his brain is already on high alert. I haven't tried it yet but I plan on bringing his Lick Stik with me next time so he doesn't have to try to chew and run.
Let them do their business first. The first couple blocks are the slowest because Kobi needs to stop and pee and couple of times before proceeding with his run.
Keep Running. If you see a reactor coming up but you can stay a decent distance from it, just keep running. Kobi has managed to pass by several reactors with minimal to no reaction because we keep moving, meaning his brain keeps moving and he never gets the chance to focus in.
Tie the leash around your waist. This allows you to keep both your hands free to run, grab the leash if you need to or get treats. This allows provides a better anchor, if your dog starts pulling towards something, slow down and lean back slightly until you pass it. Do be careful though because if they pull suddenly you can thrown all off balance.
Make the leash yucky. When Kobi gets over stimulated he starts biting at the leash. He absolutely hates apple cider vinegar so I've gone back to pouring some on the leash before heading out, that way if he tries to grab it he gets a nasty mouth full. If your dog goes grab the leash, stay calm, come to a stop, tell them to "give" or "drop it" or "leave it" and praise them when they do by giving a treat or letting them sniff for a few minutes. Once they've settled say "let's go" and keep moving. If they keep trying to get the leash once you start running again try either walking quickly for a few steps before running or lure them nose forward with a treat as you start to run, awkward but effective.
Run alone first. Jogging is exciting enough. Wait for them to get into the rhythm of it before trying to add a jogging partner or another dog. I have just started jogging with a friend and it's tough for the first few blocks since Kobi just wants to chase them and tackle them. Make sure your jogging partner is understanding and willing to jog with you and your dog, meaning they need to be willing to take breaks when you do, walk or stop when you need to and go at your pace.
Take advantage of their calmed state. Leave about a block or so of walking at the end of your run for both of you to cool down. This block is also a perfect time to throw in some training. If you've been struggling with loose leash walking, they often tend to fall into the perfect spot after a good run, reward them heavily while they are in that position building value for being there. Kobi and I have been working on "whiplash turns". I either throw a treat out or wait for him to be distracted, yell his name and immediately move in the opposite direction, marking the instant he turns his head and treating him when he catches up to me. By teaching this at the end of a run he learned it in a calm state but in a distracting environment so now I am able to use them command when he is in a more aroused state and he is able to listen.
Hopefully these tips help you have a peacefull jog with your dog! I'll get there soon I hope!