Pay someone. Preferably in single malt whisky and I'll be your start bitch.
Or you could get serious and build an all in one bike stand rear wheel roller / starter powered by a 400 Buick motor and charge all the oldies with Bulta-cos $5 to start 'em.
I reckon your return on inverstment is one two day MX meeting with three Bullys present (not including yours) they way they start.
God didn't give us knees to be brought to them. Walk on Jerr mo-fo (notice the whisky reference). We dont stop riding cause we get older, we get older cause we stop ridding.
Look at it this way, it gives you a great excuse to develop a pain killer addiction.
Warmest regards and affection,
ER