Betsy - I think you hit upon my motivation issue.
It is 3 1/2 months until my next big event and that, plus the triple digit weather, gives me every excuse and sub-concious reason not to make running (and other exercises) a priority. I am still getting out there and doing it, so to speak. However, my 6-7 days per week has become 4-5 days per week, and my long sessions have gone from 10-12 mile runs to 6-8 mile runs, etc... I think the only exercise I have been incresing my distance with lately is swimming, and that isn't as heat sensitive as running and biking. I figure as long as I stick it out during this tough period, I'll regain that motivation as I close in on my late October half-ironman in Austin.