Sowilo's warmth can drive away the chill of apathy or the fog of confusion. The ghosts and shadows of the past are chased off by the bright glow of its eternal here-and-now. It is a rune of what is and what will be rather than what has been, the force which through the green fuse drives the flower, the dawning that destroys the darkness and awakens us from sleep.
This is a powerful healing rune which can be used to shake off infections and to rebuild one's strength after a long illness. If you are weary and feel you can go no further, Sowilo can give you a "second wind" which will allow you to soldier on. It can also be used to strengthen the will and give courage and charisma: channeled through you, its force can make you burn bright as the sun.
Sowilo brings the blinding flash of mystical attainment: it is the knowledge which dazzles your senses and burns itself into your soul. But its fire is the Apollonian inspiration of poetry, science and strategy, not the Dionysian fury of madness and intoxication. This is not the madness of Odin on the Wild Hunt or his Berserkers charging madly into battle. Rather, it is the "Aha!" which allows you to grasp the answer to a difficult problem.
Sowilo is often used as a victory-rune (and was co-opted in that capacity by the Third Reich's Schutzstaffel for their SS badge). In the Hávámal Odin says
An eleventh I know: if haply I leadBut Sowilo's victory is one gained through superior tactics and insight, not through brute strength or blind fury. There is a great elegance to this rune. Much as the sun rises and sets by a tight schedule and hews on its course along a well-mapped arc, Sowilo is a rune which combines power and precision. It is the sword-strike of the skilled warrior, the orderly advance of the well-trained legion. If you are working on a project which requires that sort of discipline, you will do well to channel this rune's power and learn its lessons.
my old comrades out to war,
I sing 'neath the shields, and they fare forth mightily
safe into battle,
safe out of battle,
and safe return from the strife.
Sowilo is generally considered one of the most positive of the runes when it comes up in a reading. But, as always, this depends on the surrounding runes. Sowilo can illuminate the truth and show you the way out of the darkness. But it can also bring to light things you might rather stay hidden. Like the other runes, Sowilo is neither benevolent nor cruel. The sun can expose your failings as well as your triumphs. It shows how far you have come and how far you still have to go: it may even reveal that you have lost your way entirely. You may profit from the knowledge it brings or scurry back into the shadows: what you do with its wisdom is entirely up to you.