No apology is necessary, as fasting is generally thought of in terms of food and drink.I apologize as I thought that was what you meant. It's all good.
But as you pointed out, it could be "time" on social media or in front of a TV.
It could be "money" unspent for a week.
Or any other thing that the "skin and bones wants".
I use the term "skin and bones" in lieu of the word "flesh", so as not to mix up the fleshly mind, which is done away with at baptism, and the muscles, tendons, and so forth of the vessel the Holy Ghost abides in.