I was very fortunate to live in an area post-college with a very active running community for both DIII/DII colleges and the local USATF chapter organized track, XC and road race series year round.
I was an 800m runner in college and decided 3 things for running post-collegiately
1. I would run 2 marathons competitively. Boston and a marathon to qualify for Boston.
2. I wanted to give every distance a fair shake
3. I would be done running competitively before I turned 30.
Here is the route that that I took and what I focused on each year.
22 - 800m indoor and outdoor
23/24 - 1500m/mile indoor and outdoor
25 - 5k road & 8k XC in fall, 5k outdoor
26 - 8k XC in fall, 10k road and track in spring
27 - 1/2 marathons. ran 3 that year I think.
28/29 - fall marathon to BQ but didn't run in in time to race boston that spring. Ran boston the following spring
I never ran great times, my 5k PR is barely sub 16:30 but I had a blast moving up in distance every year and constantly seeking new challenges.
Now that I am 36 and I try to mix up my physical activity so I run, bike, swim, nordic ski, lift weights and do yoga. I don't do workouts or plan training but probably 1-2x per month I have to hop in a nearby race just to get my competitive fix. Biking and skiing get on my wife's nerves though because I probably spend more money on gear than I should.