My 3 methods for a timid male :
1) A: Put another male w/ the same genes as him in there n let them duke it out.
B: Put another male w/ different genes but genes you would not mind entering the female in there n let them duke it out.
2) Put another males shed in there.
3) Drop the night time temps down a good 4-5 degrees for an hour or 2 so they realize that the "season" or "climate" in their tub is changing and it must be that time of the year to get busy.
All males are different, but these 3 methods have all been successful for me.