Exercises to improve medium paces?

[soloequestrian]

My boy did two quite nice Novice tests today, but in both our medium paces let us down. He is quite a short horse and very 'workmanlike' - nice rhythmic paces but no huge potential for extravagant movement. I find it difficult to get any feeling of elasticity from him - he goes well in a collected pace, well in a working pace, but changing between the two can be tricky. He is quite a worrier too. I'm wondering if anyone has any nice exercises they can recommend to help with these things - transitions within paces and improving medium work while remaining calm?
Many thanks in advance.

 

[Barnacle]

Pole work, including raised poles, and just lots of practice! Also, practicing in new environments and while out hacking can be helpful.

This may sound unconventional but I also like to teach transitions within paces on the lunge with a voice command. This makes it much easier to teach the horse the aids from the saddle and you'd be surprised how amazingly quickly they learn on the ground (only takes one session with most). It's not a quick fix as you need to then translate it all into the saddle and off the harder aids but it might be something to consider if you are really struggling.