There is no later, do it now
Sometimes, when I get a WhatsApp message or an email, I'll see that I got a message without opening it, thinking "it's better to check this later". Most times I think this is the wrong choice for me and that I feel more relaxed and have fewer things on my mind when my reaction is to deal with things as soon as I notice them. I've found it useful to practice noticing when I'm thinking "I'll deal with that later" and reply with "There is no later", and then I reply or take out the trash or do whatever needs doing.
I don't think this is a useful heuristic for everyone, but I generally feel better when I follow it.
I wonder why this works so well for me. When I notice something to do and decide to deal with it later I will have to remember it again. And the next time I remember it chances are that it will feel as inconventient to deal with it then. When I don't deal with a thing immediately I often end up remembering it many times without doing it. Each time I remeber it I feel a bit worse about not having done it, and the thing can turn into a bigger thing than if I had just done it straight away. If I postpone replying to a message or email I sometimes forget to reply in time, when this happens it feels shit.
There is not later, do it now.