"I should go do something useful."
The flat statement offers no direction; it does not lead to action, only self-recrimination.
The implied judgment of yourself as not currently being "useful" is toxic. It tells you that you are being bad and lazy.
My mom died in 2006, but sometimes it's like I hear her voice.....
"Useful" is ill-defined and an easily-moved goalpost.
The idea of people needing to be "useful" is the voice of oppression. Lots of -isms hide there. Including (Tim Curry voice) capitalism.
No really, literally this is the voice of everyone who has ever guilt-tripped or browbeaten you for not meeting their standards. Every parent, every boss, every teacher, every gatekeeper. It is the voice that harmed them so much they had to pass it on rather than reckon with it.
"What could I do to help myself out later?"
Is a dialogue you can engage with. Open-ended.
Properly frames any action as being helpful to yourself. It is a kindness. Kindness is important.
Sets you up to appreciate what you did later on when you say "Dang, that folded towel was real nice, made me feel real good pulling it out of the laundry closet. Thanks, past me!" Reinforcement!!!
Doesn't put you on the spot right now. You could just as easily ask "What can I do an hour from now to help myself out later?" as "What can I do now?" You can give yourself that beautiful airlock time to mentally prepare.
Being helpful, even slightly, even to no-one but yourself, is better for the spirit than being "useful". Capitalism doesn't give a shit about helpful. It wants to use you, and it teaches you that if you are not being useful, you are by necessity, useless. Our culture, based on capitalism, implants this toxic mindset in us in myriad ways, and we carry it into our private lives where it does not belong and we weaponize it against ourselves. Never think that your value is determined by usefulness. Even when you can't do anything, you aren't useless. The concept of usefulness/uselessness is an idea that means a lot when applied to objects. It has zero meaning when applied to human beings. Expunge it from your vocabulary. Do not use it for yourself, or for others. Ever.
Fuck capitalism. Be a comrade to yourself.
Don't be my mom. (Dead but also a bitch.)