Find the synonyms of 'strenuous'.
Some synonyms of 'strenuous' include: arduous, intense, tough, demanding, exhausting, grueling, laborious, rigorous, challenging, and difficult.
Complete the following task based on the instruction and optional input provided.### Instruction:
Find the synonyms of 'strenuous'.

### Output:
Some synonyms of 'strenuous' include: arduous, intense, tough, demanding, exhausting, grueling, laborious, rigorous, challenging, and difficult.