跑 + (Modifier) + 步
跑步 (pǎo bù) is a separable verb meaning "to run" or "to jog" as a form of exercise. Because it is separable, elements like 了 or duration phrases can be inserted between 跑 and 步. For example, 跑了三十分钟的步 means "ran for thirty minutes."
我每天早上跑半个小时的步。
wǒ měitiān zǎoshang pǎo bàn gè xiǎoshí de bù.
I run for half an hour every morning.
昨天下雨了,所以没跑成步。
zuótiān xiàyǔ le, suǒyǐ méi pǎo chéng bù.
It rained yesterday, so I didn't get to run.
她已经坚持跑了三年的步了。
tā yǐjīng jiānchí pǎo le sān nián de bù le.
She has been running consistently for three years.