Got my sim to have take a brisk shower to get him energized it work but...

I got Steve to take a brisk shower a few hours before work to get him energised it worked great but just as the count down to zero suddenly his statues suddenly changed to tense oh no how could that happen on zero time for work first day on the job and it took away the 4 hours of been energised what could of course such a dramatic change in status all of a sudden. How can sims be so unpredictable and no guarantees to stay in that mood. He must be a Gemini like me moods change very fast