i'd understood that 220 bpm and take away your current age was about what you want to hit ... ~ 110 sounds like a joke to me, but i don't know for sure about that
this page says 220 minus age is not a bad estimate, but that there are better - take a look :
http://home.hia.no/~stephens/hrchngs.htm
so i'm only 2 years older than you, reasonably fit now, and i'd want to get my heart rate up around 180 for 30 mins...
basically any exercise is going to help, but the more research you do the more you will get out of it