Sun Trine Mars...

enters on December 10 (using a 1 degree orb), is exact on December 11 at 12.18pm in Kilmore, leaves on December 12.  Sun at 19 degrees and 7 minutes of Sagittarius, Mars at 19 degrees and 7 minutes of Leo.

Mars, the planet of energy, drive and passion has its brakes on as it slows down in preparation to turn retrograde soon.  Combined with travelling through the fixed sign of Leo, this gives Mars a very powerful, concentrated feel that suggests an inability to change, or on a positive note, a very determined and powerful focus.

The Sun can act like a trigger, or like a beam of light in the darkness - where it illuminates something in particular.  In this case it seems that what is being highlighted is our 'Mars'.  See which house Mars is travelling through and which houses it rules (ones with Aries and/or Scorpio on the cusp or intercepted in it) in order to get a feel for what or who is being highlighted. 

The trine is an easy-going energy that helps to 'unblock' energies: considering the current state of Mars, I think that this trine will be very helpful for getting things moving a little in terms of whatever or whoever Mars represents in your birth chart (as much as a stationary Mars can be moved anyway!).  This movement may simply be an awareness of what is going on which Mars, which will make it easier to plan for and/or deal with.