My testicals swell up when i am active and go down when resting, i have no urine infection, is this anything to worry about, not much pain?

Scrotal swelling: Scrotal swelling may be associated with fullness of the contents including testicles, veins, or fluid retention. If it is not painful, this is generally a good sign. Causes may include hydrocele (fluid collection) or varicocele (vein engorgement). These are both relatively benign and should not cause concern.

Hernia?: Is it your actual testicles, or is it your scrotum (the sac the testicles sit in). Is it one side, or both? This sounds suspicious for a hernia. This is generally not immediately dangerous, but you should see a doc to get a definitive diagnosis. If it is a hernia, you should have it surgically repaired.