I played a little guitar in high school and college but not since then. The flute is my major instrument, and it has it's challenges but does not require the hand and finger strength required for playing guitar. Arms and shoulders instead
I would highly recommend you take a lesson or two here and there even if you don't want to commit to a more formal/regular schedule. You will get such great tips and avoid unknowingly developing bad habits, especially when you are teaching yourself to play an instrument. A teacher can spot things in an instant that you would never figure out on your own. And as others have said...practice a lot, it's the only way to go. Even the pros practice for many hours a day. Start off in small amounts of time, that will help you build up stamina, endurance, and those oh-so necessary calluses. Be very very patient with yourself and have as much fun along the way as you can.
It's also possible to switch some guitars from metal to nylon strings, which are easier on the fingers, but it may not work on all guitars because the amount of tension is very different between nylon and metal strings so the strength and stiffness of the neck is a factor. The sound is obviously very different too.