Gal. 6:2 Bear ye one another's burdens, and so fulfil the law of Christ.
Gal. 6:5 For every man shall bear his own burden.
The first verse refers to excessive burdens that we share with one another; the second verse refers to the normal amount of care that each of us can carry on our own. It is not reflected by the KJV, but the Greek word translated "burden" in 6:2 (baros) is different from the one in 6:5 (phortion).
We'll offer some further detail to make the point. The first refers to heavy loads that are difficult to carry. Baros is found only 6 times in the NT; these 2 cites offer the clearest contextual clues:
Matthew 12:20 Saying, These last have wrought but one hour, and thou hast made them equal unto us, which have borne the burden and heat of the day.
Rev. 2:24 But unto you I say, and unto the rest in Thyatira, as many as have not this doctrine, and which have not known the depths of Satan, as they speak; I will put upon you none other burden.
The second word is used only five times in the NT, and it refers to anything that is carried, witn no connotation of difficulty. It is the same word used in Matt. 11:30, where Jesus says that His "burden" is light. It is also used in Matthew 23:4: "For they bind heavy burdens and grievous to be borne, and lay them on men's shoulders; but they themselves will not move them with one of their fingers."
Note that the word "heavy" here is barus -- which is related to baros. Phortion required the modifier in order to be made "heavy".
As a secondary issue, one Skeptic places the latter verse (6:5) against Matthew 19:21, where Jesus tells the rich young ruler to sell all he has and give to the poor. Would a Skeptic suggest that the burden of the poor is a "phortion"?