Can you do it now?
Should you do it now?
If the answer is “no” to either of those questions, let the task live somewhere. Somewhere that you will check, and work from soon.
Don’t keep it in your mind. At worst, you forget it. At best, you’ll have to search through your brain to find it when you need it. More likely than not, it will keep resurfacing, occupying scarce mental energy on a recurring notification that you could have put down on paper.
Let the tasks live on a list so you can be more present in each moment.