Yep, a ton of factors. People keep trying to push dogs on the physically ill where I am but it wouldn't help for me, and neither would a home bound pet coz I can barely look after myself. Its not motivation I lack, its the ability to do it safely.

Also once you have a pet and let it down by not being cognatively capable of ensuring it stays healthy hopefully services, people around you and common sense stop you getting another pet. (Sadly not always the case though).