Recently, I ran across a use of regiment that didn't feel right. That's because the author meant to use the word regimen. One little "t" at the end of the word threw off the meaning of the sentence.
So let's look at when it's appropriate to use regimen and regiment.
Regimen vs. Regiment
Regimen is a noun that refers to a systematic plan that a person follows, usually in regards to their physical or mental health, though it can also pertain to other activities (like writing). For instance, a writer may follow a regimen of at least one hour writing each day.
Regiment, on the other hand, is a military unit that typically consists of a number of smaller groupings, whether that's battalions, squadrons, or companies. It can also be used as a verb to indicate organizing or subjecting someone or something to a certain order that is usually considered strict and/or oppressive.
Here are a few examples of regimen and regiment:
Correct: My new regimen is to eat a banana for breakfast each morning.
Incorrect: My new regiment is to eat a banana for breakfast each morning.
Correct: Colonel Smith is in charge of this regiment of soldiers.
Incorrect: Colonel Smith is in charge of this regimen of soldiers.
Correct: Their entire regiment completes a regimen of physical fitness training each day.
So a trick for keeping this straight in our heads? Let's try this: Take the "-ment" in regiment and think of how it matches the "-ment" in government, most of which usually have some form of a military and/or order (sometimes strict order). That leaves regimen to mean the systematic plan a person follows.
No matter what type of writing you do, mastering the fundamentals of grammar and mechanics is an important first step to having a successful writing career.