I'd go with term limits as well. Too many people in what are essentially life terms

Plenty of countries have laws that fine or otherwise punish people that do not vote, afaik this doesn't tend to lead to better functioning democracies. I think this is a thing where the carrot works better than the stick.

They could vote for the legislation, maybe push for an amendment, that doesn't kick in for about 10 years.

e.g. starting 1 January 2036, no person can be a member of Congress who has been in office for 10 or more years, consecutively or non-consecutively. This does not apply to any person who was a Congressperson at the time that this amendment was ratified; and years served before 1 January 2030 will not count.

and/or,

e.g. notwithstanding the aforementioned, starting 1 January 2060, no person can be a member of Congress who has been a member of Congress for 10 or more years, consecutively or non-consecutively.