Not everybody is the same physically, or iscarrying the same injuries, but core strength and lots of stretching benefit everyone. Also warming up into a ride and not going like hell from the off is more important as we age especially if alot of hours are spent at a desk, driving a car, etc
@Stanflashm4n - As others have said it could be that that saddle is too low and you might be better off with it higher, or bars lower if the saddle is already at the right height.
The saddle might be too far back and to reach the bars you are curving the spine too much, too.
Sometimes you also just have to have a setup that is a bit unconventional, too, if there are injuries or defects that need to be worked around.
I suggest doing the free things first before lashing out on a bike fit that has a high chance of being a complete waste of money. get into a habit of stretching at any point of the day and when you are on the bike. Very important in the first few miles and always start riding slowly to warm up. Start riding like a scalded cat and back muscles can tighten up and cause lower back pain. Also do a bunch of spine friendly core exercises. Don't do old school sit ups!
Review your position on the bike and consider changes that put more weight onto the bars and a little less into the saddle, for example. Maybe move the saddle up and forward to change how muscles engage when pedalling, or try using lower gears and spinning instead of mashing.
You probably will end up having to buy something like a stem, or a saddle, or a seatpost etc but play around with what you have first and i know it sounds a bit hippy but really engage with the parts of you that are in contact with the bike and feeeeel what is going on. How comfortable are you really? Is something hurting that is causing you to tense up and that is making your back hurt?