I'm currently working in a software company and I am enjoying it so far. Everyone is quite friendly and gets along well together. A lot of times since I have started here my boss has asked me to attend after work activities or events on the weekend with other staff.
I don't mind things such as going out for lunch during work, but I'm not interested in doing things with my boss and co-workers after work or on the weekends. My main reason for this is that I live an hour's drive from work, and sometimes these events don't start until 8 pm or afterwards. This is okay for other staff as they all live within town, but it's too long of a day for myself when I have other things I like to get done in the evening such as going to the gym. It means getting up at 6.30 am, being in work for 8 am and then I'm not home sometimes until after 9 pm that night. I generally want to keep my work life separated from my personal one, also.
So my question is, how can I politely say no to these invitations? I don't like coming across as always turning them down, so I do go to these sometimes, but it's happening at least 3 times a month now and it's just getting a bit much.