Verb conjugation of "behalten" in German

I will put that one and the offending words. These words should not be optional, cause we need to know when a word is offending. Would it be helpful to have a counter, so you see how many words you translated?
Productivity declines when it is too hot outside. Oscar therefore closed his laptop and production unit and headed towards the lake where his pretty girlfriend was waiting for him. Once he arrived he bought a ice cream as a surprise.
My problem never was the writing part, but I did not have the courage to speak. When I did not get further, I had to use my hands and feet to communicate, which always seems a little stupid.