As long as your business is running as a tax entity type of Sole Proprietorship, then any money in or out of personal nature, or any use of other personal financial resources such as personal credit card and personal cash, are simply your own Asset = funds or resources that are yours, personally.

That means using them for business purposes increases your Equity ("ownership position") in the business. Those funds (or resources) are not Income for the business; you provided it, not from the result of a Business activity. And any removal of funds (checking withdrawal, keeping cash when paid by a client, etc) reduces your Equity in the business, because you removed the funds (asset).

Here is "the accounting formula" that explains how to track this:

Money is an Asset, so...

Assets = Liability + Equity

Assets go up, so either Debt (liability) has gone up (you borrowed funds) or Equity has gone up (you provided funds to the business).

Assets go down, so either you used it to buy other assets (furniture, fixtures, inventory, property) for the business; you used it to pay down Liability (debt service, such as paying down business credit card or business loan or mortgage principal); or, Equity has gone down (you took funds for personal use).

That is why we refer to the Balance Sheet. That formula reminds you this stays In Balance.

As long as you do not see these activities in the Profit and Loss reporting (it's not income or expense; it's Cash Flow as inflow and expenditure), you are on track.

Hope that helps.