2005 Ford Explorer takes a long time to start?

I have a 2005 Ford Explorer with around 40,000 miles and lately when I go to start it, the engine will rev for longer than usual and then it ll turn on. When I bought it used it started up quick like it's supposed to but I'm worried if this is serious or not? It starts everytime, it just takes a while, which is why I haven't taken it in yet.

So are you waiting till you get stranded to take it in? Then you get to pay for a tow truck and everything, that is, if the tow truck can find you. It sounds like you need a new battery.

Its normal for older cars to be like this, just in-case it would be best to take it to a garage to see if there's something wrong.

I'm guessing here but I think the word rev to you means cranking to me. That is the only way your question makes any sense to me. And Luke doesn't seem to be able to read the part where you said it didn't used to be like that. My question is does it do this on every start or maybe just in the morning? If all the time I'd say your fuel pressure regulator is leaking. If only in the morning then I say it still could be the regulator or a leaking injector or the check valve in the fuel pump. Anyway I'd say your fuel system is loosing it's prime.