An HGTV star who's invested in over 100 properties explains what to do if you want to buy a home, but don't think you can afford it

Once you've decided that you're ready to take the leap and become a homeowner, it can be disheartening to realize your finances aren't up to snuff.

But if you're committed to saving up for a down payment - and willing to make a few financial sacrifices - don't lose heart.

Scott McGillivray, the host of HGTV's "Income Property" and a real estate expert who's invested in over 100 properties, has a trick to help wannabe-homeowners reach their goals faster: the practice mortgage payment.

McGillivray suggests coming up with a ballpark figure for the type of home you can afford - a good rule of thumb is to make sure your total monthly housing payment doesn't consume more than 30% of your take-home pay - and calculating what a realistic mortgage would cost. From there, try putting the equivalent of that hypothetical mortgage payment into savings each month.

"If the mortgage payment in your price range is going to be $1,500 a month, for instance, I would start putting $1,500 a month into forced savings in some capacity," McGillivray told Business Insider.

"Let's say you do this for a year before you buy a home," McGillivray continues. "It proves that you can consistently put aside enough money to cover your mortgage payment, and at the end of the year you'll have saved $17,000."

It's not a perfect model for what it would be like to pay a mortgage each month, since you're likely still forking over money for rent, but it proves that you're dedicated to the process and willing to make financial sacrifices in order to afford homeownership.

"The truth is, if you can't do that - if you can't put that money aside and you can't actually keep those savings every month - you may not be prepared to make your consistent mortgage payment," McGillivray says.

If you're not able to put that much aside each month, but are still dead set on buying a house, you might want to consider another savings method, such as cutting back on expenses or matching your savings to your discretionary spending.

However, no matter what, make sure that you invest time in saving up for a dedicated down payment instead of simply draining your savings or other assets. Purchasing a house often comes with a flood of additional expenses, and you don't want to be caught unprepared.

"Unlike a rental arrangement with a one- or two-year contract and known termination clauses, defaulting on a mortgage can do major damage to your credit report," certified financial planner Jonathan Meaney previously told Business Insider.

At the end of the day, it's better to be safe than sorry, and practicing your mortgage payment ahead of time is one way to help yourself get there.