Most people in their 40s have children or teenagers and since February 14th falls on a school and a work day, the fun of celebrating the holiday usually takes a back seat to soccer practice and piano lessons and work. So, I suggest celebrating it on Saturday or Sunday the 12th or the 13th instead just to get the most out of the holiday.

Again, these suggestions can be considered for birthdays and anniversaries as well.

First:  Make arrangements for a reliable sitter on either day you want to surprise your spouse or loved one with children.
Second: Clear your partner’s calendar for the day – make sure you pick the day with the least pre-arranged appointments for the children and their school events.
Third: Organize a slew of events or activities for the two of you to do for the entire day – this could be an entire day spent in the country or a metropolitan city, depending on where you reside – do the opposite. For example for those living in the bay area, consider a day spent in downtown San Francisco sightseeing, having afternoon tea, a museum visit or a show or dinner and dancing and if all goes well, spend the night in a hotel downtown.
Fourth: Take her to places she has never been or a special place the two of you went on your first date for dinner.
Fifth: Buy her a special small gift (souvenir)  from the place you decided to take her.
Sixth: Take a photo of the two of you in black and white and then frame it in a 4×6 silver frame.  Then place it on her nightstand the night before  Valentine’s Day, so that when she wakes up in the morning she could see it.