Yes I know that life gets busy and sometimes it's easy to forget about Steemit.
Personally I think you should never feel obligated to post, just share whatever you think is fun to write about. But still, maybe set yourself some personal guidelines (for example: 5 posts a week) just so that you don't forget about posting alltogether.
And apart from posting, engaging with the community and talking to other steemians is just as awesome!