Select the correct word endings in each choice.

In the
Choose...
of the
Choose...
I
Choose...
to be the fastest runner, but I stopped thinking like that; now I'm
Choose...
on being a long distance runner.

To select the correct word endings in each choice, we need to identify the appropriate forms of the words.

1. In the (preposition: "in" is correct here)
2. Choose... (verb: "choose" is correct here)
3. of the (preposition: "of" is correct here)
4. Choose... (verb: "choose" is correct here)
5. I (pronoun: "I" is correct here)
6. to be the fastest runner, but I stopped thinking like that; now I'm (gerund: "being" is correct here)
7. Choose... (verb: "choose" is correct here)
8. on being a long distance runner. (gerund: "being" is correct here)

Therefore, the correct word endings for each choice are:

1. In the
2. Choose
3. of the
4. Choose
5. I
6. being
7. Choose
8. on being