I've found avg speed was something to obsess about when I first started riding but now I don't worry about it. I'm not competing,I'm not getting paid,I'm not a professional,so I don't have to have that be a factor on daily rides. Ride with someone faster,or better than you and it will make you faster. When I ride with my DH I push myself to keep up and my speed goes up. I like to do this every so often to show myself possibilities. He does this this himself during racing season,he will ride track races he's not going to win to condition himself for road races he can.
I like bikes, sometimes more than my husband