What to do with energy you can´t use?

I gained so much energy by removing the stress from my life, but now I´m forced to sit at a desk all day. Doing... Not much.

An earlier post was about downgrading in jobs, and loosing the stress of a hard job. Because of that I gained a lot of energy and became happy again. 5 months later, and I´m starting to get a little bored now and then. Not completely, just a little.

My body has the energy to exercise or run around, especially in the morning, but I can´t. My job is to be available when someone calls, and answer emails. Everyday I get between 5-15 cases, which usually take me 3 or 4 minutes per case. So what should I do the rest of the 7,5 hours?

Note, the computers are restricted and I´m not allowed to have sound. I can read a book in pdf, watch a movie with subtitles, play games, check Steemit and learn Portuguese. But after months of doing this, I´m starting to get bored. Not constantly, usually it starts in the afternoon. About an hour after lunch. most calls and emails I get in the morning, so the afternoons are a complete self-entertainment.

Sometimes I´m so bored that I almost fall asleep. Even coffee doesn´t help. I´t just counting until it´s 5 o´clock.

Of course the are small exercises to keep me busy, like stretching your legs in front of you or moving your arms. But this does not help me to retain that energy I have in the morning. After work I like to do a workout, but I always feel like I don´t have as much energy as I have in the morning.

Any ideas how I can save my morning energy for my after work workouts, and not let it go to waste?