Something I had to do at short notice on Sunday, and this was what I scribbled on the back of the envelope:

Holy Father,
it is through his death on the cross that your Son leads us into life;
we ask you to bless this cross (+) that we who lift it high and follow it
may be inspired and encouraged by his example
and enabled by grace to walk in his footsteps;
this we ask, in the name of Christ our Lord. Amen