The puzzle's end is just the beginning. Add the starting numbers, but don't overlook the simplest connections. Then add the end numbers for a complete sequence.

12345678910111213
Across
  1. 2. Opposite of up.
  2. 5. Shedding tears, often in response to emotions.
  3. 6. Assists or aids.
  4. 7. Definite article in English.
  5. 8. Opposite of fast.
  6. 12. Difficulties that need to be solved.
Down
  1. 1. Conjunction used to connect words.
  2. 3. Measure of heaviness.
  3. 4. Possessive form of the term referring to existence.
  4. 9. Above or higher than something.
  5. 10. To preoccupy the mind excessively.
  6. 11. Personal pronoun for oneself.
  7. 13. Expressing the relationship between a part and a whole.