Each day is composed of 24 hours. Every person has 24 hours to live his daily life. Yet, time is not within the control of individuals. It cannot be stopped , it cannot be changed. It is both unbending and bending depending upon how a person uses the time he has. To me, college is like running a marathon. You have to keep running until you get to the finish line.
That passage above is how I would have written your run on sentences. Just remember, you can easily avoid run on sentences by simply writing shorter sentences and using a period instead of a comma whenever possible.If I may say though, there is no connection between time, your description of it, and why college is like running a marathon. There is a missing connecting sentence in the presentation. This is an incoherent and non-cohesive thought presentation. You should think about ironing out the missing information before worrying about your run-on sentences.
I would say that holt is right as you can simply avoid run on senteces by writing smaller sentences and avoiding the use of commas to try to avoid longer sentences.
