I think my phrasing wasn’t very good. Creating positive experiences for oneself makes sense regardless of life after death.

However, some behavior is motivated by long term consequences. These matter less or differently if you believe there is no afterlife.

E.g. some people behave differently in at a party with people they will never see again than a party with e.g. colleagues and family.

Or many people leave public toilets dirty while they keep the one at home clean.

People who believe in an afterlife might have the mindset they will see people from their life again and they might (if they believe in reincarnation) walk the earth again. So it’s a motivation to keep the environment liveable for future generations (beyond just family and kids) or to be nice to people you likely don’t meet again.

The behavior could be identical for people with or without a belief in an afterlife but their motivation and thought process behind it might be different.