commas - What is the correct punctuation to use when using "like I said" in a sentence?

I don't know how to properly connect the first three words of this sentence to the rest of the sentence:

Like I said: this is a problem for your doctor, not your drug dealer.

I feel like that colon is incorrect punctuation. Should it be replaced with a comma? Or should I use some other punctuation?

Answer

b. In some cases a person's exact words may be treated as either a
direct or an indirect quotation, depending on the kind of emphasis
desired.

The chairman himself said, “The staff should be told at once that the
rumors about a new building have no foundation." [The use of quotation
marks emphasizes that these are the chairman's exact words.]

The chairman himself said the staff should be told at once that the
rumors about a new building have no foundation. [Without quotation
marks, the emphasis falls on the message itself. The fact that the
chairman used these exact words is not important]

—Gregg Reference Manual. Tenth Edition. 65.

Also, use and instead of the comma for parallel structure: "...for your doctor and not (for) your drug dealer"

CORRECT:

Like I said, this is a problem for your doctor and not your drug dealer.