It must often to be so

"(...) Are you coming?
'Yes, I am coming, ' said Frodo. 'The Ring-bearers should go together.'
'Where are you going, Master?' cried Sam, though at last he understood what was happening.
'To the Havens, Sam,' said Frodo.
'And I can't come.'
'No, Sam. Not yet anyway, not further than the Havens. Though you too were a Ring-bearer, if only for a little while. Your time may come. Do not be too sad, Sam. You cannot always torn in two. You will have to be one and whole, for many years. You have so much to enjoy and to be and to do.'
'But,' said Sam, and tears started in his eyes, 'I though you were going to enjoy the Shire, too, for years and years, after all you have done.'
'So I though too, once. But I have been too deeply hurt, Sam. I tried to save the Shire, and it has been saved, but not for me. It must often be so, Sam, when things are in danger: some one has to give them up, lose them, so that others may keep them. But you are my heir: all that I had and might have had I leave to you. ..."

Sam & Frodo in The Grey Havens - The Return of the King
The Lord of the Rings (1955) - JRR Tolkien
Harper Collins