My dad worked shifts, so often I'd go a week at a time without seeing him (say, if he was on back shift). But I do remember him taking me to the park to play football with me, taking me fishing (twice - I didn't like it; he took Scott loads though) and loads of other things.
I try - even if we're just inside, I make sure I'm watching stuff with my kids every day (an excuse to sit with them and talk).
It isn't difficult. It isn't work.