I'm a guy.
I swam, biked, played soccer.
High school junior & senior years I ran XC & track. HS PB's 57" 440y, 4:44 mile, 10:40 2-mile.
College freshman 4:20 1500m, 10:00 2-mile.
Age 35 16:04 5,000m, 15:20 3-mile.
Age 44 3:28 3/4 mile, 7:41 1.5-mile.
Age 48 16:41 5Km.
Age 50 4:58 indoor mile.
Age 52 16:38 5Km
Age 50-52 Outdoor miles 4:48, 4:46, 4:41
Success & satisfaction my come early, or it may come much later in life.
I am happy with my longevity, age 59 now, and very healthy.
Many faster than I was are now in poor health.
Lifelong fitness and health is the most rewarding goal.
I reached my best fitness thru consistent aerobic training at 65-70% of max heart rate on soft, hilly trails wearing nearly flat shoes. 65-75 miles per week for 4 months, patiently building my aerobic engine.
I do doubles,
Mon Tue Wed Thu
A.M. 3 - 3.5 miles soft level grass
P.M. 7 - 8 miles soft hilly trails
For the P.M. I alternate the ratio of running level grass & hilly trails.
Mon Wed Fri hilly trails
Tue Thu level grass
Mon Wed Fri level grass
Tue Thu hilly trails
6 - 8 miles easy, trails or grass
12-20 miles very easy, HR 130 - 150 with ultrarunner friends over hilly trails, hiking when needed to keep my HR down.
2nd - 3rd months just push the edge of 155 bpm.
Easy pace but quick steps uphills, faster pace but controlled HR downslopes.
Steady, steady, steady.
The runs get faster at the same heart rate, 5 - 10 seconds per mile week to week.
End of run 2-minute HR recovery should be to about 115 - 120 bpm.
120 bpm is your marker.
In the 4th month, I run faster on gentle downslope sections (lower HR), gradually getting quicker steps with more power.
End of run 1-minute recov 120-130,
End of run 2-minute recov 120-110
In the 5th month I begin peaking, easy during most of the P.M. runs, then surging over the last 2 miles.
End of run peak HR 170-180,
1-minute recov to 130,
2-minute recov to 120 or just under.
This is your big indicator of successful aerobic engine building: At the end of your P.M. run surges feeling comfortable at a high HR, and your HR recovers 50 - 60 beats or more in 2-minutes.
A.M. runs are recoveries for the P.M. runs.
Use physical route checkpoints (not GPS pace or distance)... like is done in the Tour de France. Let your brain learn to compress the time to set section personal records.
Run in a pool every so often as needed to keep fresh legs. Bicyling...easy spinning is also good.