I highly recommend either going on other people's forum rides or organising some yourself!
I have a small envelope of time in a morning to go for a ride before interest wanes, if I do not get out of bed whilst I have the keeness to go, then the chances diminish as the time passes. After about an hour, I will start to think that I could be 16 to 18 miles from home by now and at that point, I will go or not go.
But if I am doing something different, club ride or event, or as Colin says, a forum ride, then I'm restless, itching to go all night, and there's no stopping me. Alternatively, buying something new to try on the ride, looking at a map and finding something interesting to go and look at where you have never been before, set up a challenge for yourself, or do some interesting training all helps.
At the moment I have got hooked on long rides with low heart rates which has got me all keen again because of the big benefits I am seeing. On Saturday, I climbed a very steep hill and I was facinated by the fact my heart rate never got above 133, apart for the last 100 yards when I gave it some umph to finish it off and hit 151. That hill usually has me in the 170+ from the bottom to the top, but on Saturday, I got up just as fast as normal. Its hard to do, as someone will always fly past you and its hard to take up the challenge, but its got me very motivated.
If I was to look at my stats, the biggest percentage of rides happen in a morning.
Since 2009, I have done the following, not counting commuting:-
Mornings - 268 rides
Mid Morning - 51 Rides
Afternoon - 26 Rides
Evening - 24 Rides
Night - 1 Ride