It is the first step that is troublesome

Proverbial Meaning: When one plans to embark on a new a project it is often getting started in the first place that is the most difficult thing to do.

Literal Origins: When babies are learning to walk it is always the first step that is the greatest achievement, after the first step is accomplished learning to walk becomes easier every day.

Common Usage: This proverb is very popular in the form, "The first step is always the hardest" or something very similar. Though, ironically, it is used most often when talking about giving something up, especially an addiction.