Balancing on the blocks...

In addition to stretching, I suggest some strengthening exercises such (1-2 sets of 15 with or without hand weights):

• Box Step-ups - these will strengthen your quads.  Look for 12" step ups.  Don't worry about lifting your knee like the video. If you can't find a box, find stairs.
• Lateral Box Step ups - This will help with balance and strength
• Lunges - both forward, backward, and laterally.
• Deadlifts - with or without weights.  These will strengthen your lower back and glutes which are important to stability
• Calf raisers - strengthening the calves will make it easier to step up on blocks and help you push off the blocks.

As Allen mentioned, try the track start which is the same as a grab start, but with one foot forward and one back instead of both feet at the front of the block.

If you have neuropathy, this will mess with your balance, so I second what Allen mentioned about one leg balancing (10 x 15-20 seconds) will help as well.  Eyes closed is tough!

68 y/o here - this is a great list of dry land activities.  Try doing the squats/dead lifts with a pair of 10 lb dumbbells (helps to develop those small balance muscles ) you can also try kettleball squats (holding a weight over the center of your chest).   For ankles try doing this during some morning lying on your back "in bed" stretches - (I do this to manage some disk issues) - pull one knee to your chest and feel the stretch in the lower back and hammy.  Now "paint the alphabet" with your toe by rolling your ankle up, down, right, left while pointing your toes.  Do each letter twice and you'll be surprised how it activates the muscles in your upper shin.  I also a stretch pulling a my knee up to the opposite shoulder to a 20 count (twice per leg).  Final "pretzle"stretch is put one knee up and cross your other leg over. Next grab the shin of the lower leg and pull it towards you to a count of 20 / twice per leg.   Pro tip here -  go onto Youtube and watch different videos that show you the dos/don'ts for each of these exercises. Don't let bad form ruin your day :-)

68 y/o here - this is a great list of dry land activities.  Try doing the squats/dead lifts with a pair of 10 lb dumbbells (helps to develop those small balance muscles ) you can also try kettleball squats (holding a weight over the center of your chest).   For ankles try doing this during some morning lying on your back "in bed" stretches - (I do this to manage some disk issues) - pull one knee to your chest and feel the stretch in the lower back and hammy.  Now "paint the alphabet" with your toe by rolling your ankle up, down, right, left while pointing your toes.  Do each letter twice and you'll be surprised how it activates the muscles in your upper shin.  I also a stretch pulling a my knee up to the opposite shoulder to a 20 count (twice per leg).  Final "pretzle"stretch is put one knee up and cross your other leg over. Next grab the shin of the lower leg and pull it towards you to a count of 20 / twice per leg.   Pro tip here -  go onto Youtube and watch different videos that show you the dos/don'ts for each of these exercises. Don't let bad form ruin your day :-)