I have poor muscular endurance. Any suggestions?

[Axolotl]

I can run fast, but I get tired before I can complete even an eighth of a mile.

[Ad Bot]

[Flamecannon]

treadmill and progressive yet subtle jogging over a weekly stretch, starting out slow then going deep in the middle, then looping the process

[Otis Da HousKat]

Stop running fast and run for longer periods of time if that's what you want?

[Big Brother]

Try and use a treadmill for like, 15 minutes a day or something quite minimal