Question

Which lines from the poem express the view that life is too short and we should enjoy it while we can?
Loveliest of Trees

by A. E. Housman

Loveliest of trees, the cherry now
Is hung with bloom along the bough,
And stands about the woodland ride
Wearing white for Eastertide.

Now, of my three score years and ten,
Twenty will not come again,
And take from seventy springs a score,
It only leaves me fifty more.

And since to look at things in bloom
Fifty springs are little room,
About the woodlands I will go
To see the cherry hung with snow.

   

Answer 1

Lines 5, 6, 7, & 8  all express life is too short and we should enjoy it while we can. The lines all under those might also go with life is too short feeling.

Answer 2

I believe the answer is: Lines 5, 6, 7, & 8

Now, of my three score years and ten, - could be interpreted as years gone by without the author realising it.

Twenty will not come again - Could be perceived that you cannot reverted to your prime years

And take from seventy springs a score,

It only leaves me fifty more. - could be perceived as an advocate to live your life to the fullest.