To me I believe it means; do not be discouraged with your present accomplishments, keep planning and preparing for the future. That way, you have a better chance of doing much better. In other words, the past is gone but the future is still to come.

My interpretation is that we shouldn't focus on results but rather by the experiences and processes. It is not about what you achieve but rather about what you are working towards.

I think this quote implies that we should not be satisfied what we got today but to continue to for for future as well.

It means that it's more important to be prepared for the future than to enjoy today without considering the possible consequences of not being prepared for the future.