In THE THREE, you have options within specific categories...
(1) A food/drink (2) A media or social media item (3) Something of your choice.
A FOOD / DRINK
This is the most important of The 3 because every example of fasting found in scripture involves some type of food fast. Take an honest look at your eating/drinking habits and ask what the Lord might need you to give up in order to hear from Him more directly. It could be as simple as coffee/caffeine or as involved as removing wheat/grain from your diet. The main thing is to "starve the flesh" to focus on God, so be intentional about what you choose. If your family is fasting together, you might have your kids choose something else entirely that more suits their habits (i.e. chips or candy).
A MEDIA OR SOCIAL MEDIA ITEM
Considering the way we consume media in so many areas of our lives, it could be argued that if Jesus called us to give something up today it might be media even more than food. But within this constraint there must be some forethought. For instance, it may be possible to give up Facebook or Instagram but impossible to give up email or texting because your work depends on it. It might be more beneficial to cut out TV time at night so that you can spend time reading scripture or leading your family in devotionals. The goal is to cut out media that would keep you from focussing on spending more time with God or that would distract you from hearing HIs Voice.
SOMETHING OF YOUR CHOICE
What else in your life is God calling you to do without? In the first two of THE THREE it will likely be easier to choose what to fast from because so much of our daily choices revolve around food and media. For this third item, spend some time in prayer asking God what He wants this item to be. It could be that He asks you to fast from one more thing or it could be that He ask you to add or enhance disciplines for your life such as....
- tithing/financial stewardship
- daily quiet times
- how you spend your day off