Like a few out there I did my cruciate playing football when I was 26 (now 33) and after keyhole in March I put on a couple of stone and really struggled to get through my overs that season (even with my military medium), so started to hit the gym (both cv and weight sessions), this was quickly followed by road running - my running season was start serious training after Christmas and do a 10k + half marathon just before the season as a motivator and I'm all set for early spring with a bit of gym / running over the summer.
However I then managed to damage my Achilles in 2009 twisting and turning when batting (don't think 13 overs straight after helped) so again under the knife. Difference this time is a controlled diet, I don't do so much road running due to the impact but as you get older you need to do something (cycling, cross trainer but with a bit if interval training to improve fitness).
Every season I see some of my club mates who rock up and really struggle early season with months of no or little exercise. Cricket (especially batting) can be frustrating and if fitness is on your mind too, your confidence takes a knock!
That said I have a sweet tooth so I always seem to put on weight over christmas, so its back to the gym to do a bit around work and family life. If its general cardio fitness you want and your pushed for time or motivation I would really recommend a few spin classes a week no matter your age!