If you are targeting runners, I'm sure that you have targeted actual races, where you can be a vendor and sell coffee to the spectators as well. To find running groups, try Facebook Groups, there are a ton of running groups in different towns. Also look up fitness/shoe stores as sometimes they put together running groups.

- Podcasts about marathon running,
- giving samples during marathons,
- put branding on swag given to marathon runners,
- advertise on treadmills in gyms or other equipment used for running marathons,
- spray messages on the running paths known for people training for marathons...stencil for coffee beans or a cup full of coffee spilling out a little every mile until they reach the end of the path and say "refuel with 262 coffee" and have a coupon stand or QR code for them to scan for a discount
- advertise on blogs for runners (display ads, programmatic, guest posts)
- sponsor local running groups with swag or free glow in the dark coffee beans to tape on their shirts or shoes when running in the dark + brand name

I've seen guys selling coffee at traffic lights and intersections. They weren't targeting runners (not sure why a runners are a target - maybe I have the wrong definition), they were targeting people stuck in traffic during peak hours.