Anyone who has faith in God is not going to live a day without thinking of him, but even if he were to forget, there would be no mortal sin, because mortal sin requires full knowledge and consent and the act must be grave. If I forget to praise God, it is not done with full knowledge and consent, because I forgot.
In a typical day no one has the excuse of forgetting.
Lets run a typical day for me before my awareness of what Mortal sin is.
5:00 AM get up
5:01 wee wee
5:02 brush teeth and other hygiene stuff
5:10 Make coffe.
5:15 Sit at computer and diddle daddle
6:00 leave of work
7:00 to 4:00 work
4:00 leave for home.
5:00 Eat Dinner (or fix dinner if I got home before me wife did)
5:30 ish snatch a kiss from wife
5:30 Watch News
6:00 Shower
6:10 to 7:00 diddle daddle on the computer
7:00 to 10:00 watch TV
10:00 Bed
and then it starts all over again.
I had full knowledge and consent and grave matter for all the above things.
As you noticed that God was not part of the Day in any sense unless of course you want to use the kissing the wife as a example.
What does our Penitentient Rite say:
I All: I confess to almighty God,
and to you, my brothers and sisters,
that I have sinned through my own fault,
in my thoughts and in my words,
in what I have done,
and in what I have failed to do;
not
and in what I have forgotten to do.
Do you really think God is going to buy the “I FORGOT” excuse?
Nobody can tell me that everything they did in a course of a day was more important than loving God so they forgot to offer a 10 second prayer?