How much have you stretched though? Stretching allows muscles to relax.. turns them into jelly. Watch an Olympic athlete before they do their routine; they look like jello.I used to walk everywhere all of the time, plus running, long boarding, and all cycling a fair amount and sometimes hiking.
Are you sure it's just weak muscles? I also used to go to the gym on a regular basis for a couple of years. I'm still in fairly good shape, but definitely not compared to before. I think I could have some arthritis in some areas due to hurting myself.
Is it true though that if you hurt yourself in an area and it causes chronic pain on and off does that mean that it will stay like that for life? is there any methods to relieve the pain at all or to lessen it at all besides drugs? I never had any pain in my body until I started becoming physically active on a regular basis.
Not stretching is the number one cause of pain. So I suggest full body stretching before you make any conclusions like arthritis or whatever. If for some reason it gets worse, you may be injured and seeing a doctor / physical therapist would be best. I don't specialize in treatment so if it's something bad then get different help. But to me it sounds like it can be corrected with stretching due to the muscles being hard, due to lots of physical activity possibly without enough stretching, and due to the description of the pain.
I can give some stretching tips:
the feet and the hand posture is very important in a stretch - dorsiflexion helps flex the glutes whereas plantar flexion helps flex the quads. If your quad is tight then working on your dorsiflexion should really help.
Stretching the back helps shoulder flexibility and hip flexibility. This is probably another area you need to work on considering you are a male who is physically active.
When you stretch make sure to do it often, to relax the muscle you are stretching, to move slowly, to never exceed a position you can't hold for longer than 5 seconds, and to breathe deeply throughout the hold. Make sure the whole body is warmed up before the stretch and make sure you work on both the upper and lower body particularly around the hips and shoulders. And I emphasize RELAX. Flexing the muscle is not good.
People who often complain of shoulder pain or lower back pain due to working a desk job and not stretching. They are putting too much stress (weight) on weak points and neglecting spreading the weight around for the whole body to bear (AKA proper posture).
It sounds like that is your problem and it's fixable if that is the case.