今既不如昔，后当不如今。这句话意味着我们现在的生活虽然好，但未来可能不如现在。然而，我们不能停止前进，而是要继续努力，以保证未来的成功。

回顾过去，我们可以看到许多改变和进步。科技和医学的进步让我们的生活更加舒适和安全。人们对环境的关注也越来越重视，许多国家开始采取措施来保护环境。此外，社会的多样性和包容程度也在不断提高。

然而，我们也面临着许多挑战。全球气候变化和环境破坏对我们的生活产生了巨大的影响。人们之间的分歧和冲突也在增加，这可能导致更多的战争和不和谐。

尽管如此，我们不能放弃。我们必须继续前进，尽可能地克服我们面临的挑战。我们需要更加关注环境，采取更多的行动来保护我们的星球。我们需要更多的包容和理解，以减少社会的分歧和冲突。

总之，今既不如昔，后当不如今。我们必须珍惜现在，同时为未来努力。只有这样，我们才能保证我们的未来更加美好。

Translation:

The Chinese saying '今既不如昔，后当不如今' implies that although our current life is good, the future may not be as good as the present. However, we cannot stop moving forward, but rather continue to work hard to ensure future success.

Looking back at the past, we can see many changes and improvements. Advances in technology and medicine have made our lives more comfortable and safe. People's concern for the environment is also increasing, with many countries taking measures to protect it. In addition, social diversity and inclusiveness are also on the rise.

However, we also face many challenges. Global climate change and environmental damage have had a huge impact on our lives. Differences and conflicts between people are also increasing, which may lead to more wars and disharmony.

Nevertheless, we cannot give up. We must continue to move forward, overcoming the challenges we face as much as possible. We need to pay more attention to the environment and take more action to protect our planet. We need more tolerance and understanding to reduce social differences and conflicts.

In short, '今既不如昔，后当不如今' reminds us to cherish the present while striving for the future. Only in this way can we ensure a better future.