It is easy to fall into the habit of writing how one feels (especially when writing poetry). Focusing on how you feel will give your work a childishness that you did not intend and make it difficult to show instead of tell.
Personally my crappiest poems have been born when I was trying to write how I felt; especially if I used words such as ‘feel’ ‘like’ ‘want’ ‘I’ (‘I’ is actually the biggest culprit of the lot!). I hate ‘I’ poems. Let me drop an example for you: