"It's not that we have a short time to live, but that we waste much of it. Life is long enough, and it's been given to us in generous measure for accomplishing the greatest things, if the whole of it is well invested. But when life is squandered through soft and careless living, and when it's spent on no worthwhile pursuit, death finally presses and we realize that the life which we didn't notice passing has passed away. So it is: the life we are given isn't short but we make it so."
-Seneca, "On the Shortness of Life"
Sometimes we have to stay in bed all day, we just don't have the energy to rise and face another day. That's okay, we can't overwhelm ourselves.
Sometimes we have to binge watch a TV series and that is a week just sitting and staring at a screen. That's okay, we enjoyed ourselves and did something memorable.
Sometimes we spend a lot of time reading philosophy books and articles online. That's okay, we're learning something and perhaps enjoying it.
Sometimes we work 60 hour work weeks. That's okay, a little extra money here and there can increase the quality of our life by a little bit - so long as this job isn't the only thing we're spending our time doing.
There are so many ways to waste life away, we can't go on adventures every day unfortunately. But that is why long term goals in life are important as well.
On the first read of this passage, one might think that Seneca is over-generalizing here, as many people die rather young and still others spend their lives without the opportunity for great accomplishment. It's important to remember Seneca's audience here: people who are able to read his work and who proclaim that life is short.
Those people are capable of accomplishing the greatest things, although these "great things" aren't necessarily in reference to solely material achievements. Moral discipline is seen as one of the greatest achievements by Stoic thinkers. In line with that thought, anyone who is capable of reading the words in this passage would be capable of cultivating that discipline.
The more wisdom a person acquires in their life, even through reading the works of philosophers, the greater the quality of life they'll have. But, like the 60 hour work week, moderation is good.