Don't rush it. Give yourself time to recover.
I had pneumonia in Jan 2010. I was ill at the weekend, couldn't return to school (work) at start of term and ended up in hospital the following weekend.
I didn't go back to work until after the following half term - so 7 weeks off work. My Gp wouldn't sign a fitness to work certificate.
he did suggest gradually building up my energy levels - so having the odd lunch out, he let me pop in to work to say hello to the staff/children, I had a weekend away, etc. Its all part of the recuperation. Don't go too fast or you will end up in bed again - luckily I had a DH, DD, family, friends and colleagues (inc my HT) keeping me from doing too much - and my GP was fabulous.
Also make sure that you are continuing to be checked. It took 4 lots of varying antibiotics to clear everything, and I needed an inhaler for a year or two afterwards as well. My lungs were clear - have those continuing x rays to make sure -but I needed some support from the inhaler at times.
It will take you a few months to feel fully fit and healthy and you will be more susceptible to other bugs and viruses, as your body is still recovering.
Take care of yourself and listen to your body carefully.