one way you might try to mix up 3 sessions... on a time not distance basis, 1 long steady (hour ish) 1 short bit faster (30 mins at most) and either another of those or dare I say (having never bothered with them) something structured such as intervals work, but under guidance of someone who knows what to do at first (local club session maybe?) - so you can reduce chances of injury.
ok, give it time and patience then...
one way you might try to mix up 3 sessions... on a time not distance basis, 1 long steady (hour ish) 1 short bit faster (30 mins at most) and either another of those or dare I say (having never bothered with them) something structured such as intervals work, but under guidance of someone who knows what to do at first (local club session maybe?) - so you can reduce chances of injury.
don't just jump into that, build into it slowly.