First, all you have to do is find other ways of playing with the kids. 'Teaching' games?...for instance? Pass on some of your KNOWLEDGE/WISDOM!!! THAT is a waaaaay more important legacy to leave behind than simple piggy-back rides while they do add to pleasant memories. ;)
A story for you: I once had an old cat. I had to keep him away from all other animals because he was born with a chemical imbalance in his brain which made him SUPER territorial and aggressive. He stayed this way to a large degree despite having him neutered. I even had to harness and tie him like a dog to keep him from getting chewed up by some other animal (he'd attack) ...wild OR domestic... or becoming 'road pizza'. I had a neighbor who dubbed him "p_u_s_s_y on a rope"!!! LOL! :D (But it is sad that TR can't recognize __CONTEXT__ of a word!!! That word was once a synonym of __CAT!!!__ :| ) He was a 'house cat' but was allowed to come and go in and out of the 'house' ON his rope as he pleased unless it was night time or there was inclement/extreme weather.
Several years before I had to have Leo euthanized, I took in a female cat who was left out in the winter with temps in the teens and over a foot of snow on the ground. (Misty's original owner died and the relatives abandoned her while emptying the old lady's apartment.) By then Leo had settled down to the point where I could 'train' him to tolerate other animals in 'his' (MY) territory. From a four week old, when I found, him I had instilled that __I__ was 'Alpha cat'!!! :D
So, he learned to tolerate Misty (as I named her) since I could not, for the life of me, find another good home for her at that time. I took her in in the first place because we had way too many feral cats around and once they 'go wild' they eventually die horrific, heinous deaths (...entirely another subject; not for here). I didn't want Misty to die of hypothermia and frostbite which domestic cats are extremely prone to. I also didn't want her getting pregnant, perpetuating the feral/pet overpopulation problem. What I didn't know at the time was that, evidently (as you'll see below), she had come into heat just as she was abandoned (yes, cat's have a 28 day cycle just has humans, horses and some other animals have) and she had already 'done the deed' before she found me.
While trying to find her a home, I thought that she was only gaining weight because I (have always and always will) free-choice feed all of my animals. WE eat WHEN we are hungry, why shouldn't they?...unless there is the human table-scrap obesity problem going on (yet ANOTHER subject). Anyway, after a couple of months (the gestation period for cats) it finally DAWNED on me that she was in deed 'with SURPRIZES'!!! Three of them, all females. I did manage to find a home for one but not the other two. I did so by allowing one (taking turns) at six weeks old (the PROPER time to wean kittens, puppies, foals and most other domestic animals) to ride on my shoulder every time I went out so a lot of people could see them.
So now (in this particular time period) I have Leo, the 'old man' and Misty, the 'poor waif' ...who had become a mother with two younguns remaining at home...a total of FOUR cats in a __900 square foot__ two bedroom apartment with me and my husband!
NOW, my POINT: Through learning to tolerate Misty and her kittens, Leo started perking up. So did my sickly husband! Leo became playful with the kittens who, once I could trust him with them, relentlessly 'attacked' him and pestered him into 'submission' :D !!! Unfortunately, by then, he was old enough that with about two years of that, as you said the 'kids' had worn on him a bit. BBut NOT Larry, my husband!!! Pepper and Squeaks...especially Squeaks were especially 'touched' cats!!! Larry LOVED playing with them and watching their CRAZY antics. Squeaks could really come up with some 'doozies'!
At this time, the plot THICKENS! I'm in school and putting in 60-80 hours a week in on school work. At the end of my first semester I had exactly five ...FIVE (5)... DAYS to recoup when Larry has to have surgery. I spent the summer nursing him back to 'health' and THEN __I__ have to have surgery!
Two weeks before I go into the hospital I find a whole litter (of FIVE!) kittens DUMPED in a remote area where I like to go to unwind and commune with nature. It's 105 degrees in the shade and very humid with no rain in sight! So I again, as usual, am 'The Rescuer'! I immediately find homes for FOUR of the kittens ...to my relief!
BUT the fifth (the runt of the litter) was originally found with his eye 'glued' shut and swollen to the size of a garbanzo bean on a head tinier than a golf ball! He fit in the PALM of my hand (while his siblings were twice his size). SO as soon as I saw his problem (when I first found the litter) I did on the spot triage to find out if this poor little creature even STILL had an eyeball or if I would have to have him euthanized AT FOUR WEEKS old!!! THANK God I did find that eyeball, but took him to my vet anyway to have the infection cleared up. We could only wait to find out if he could see with it. The infection was GONE before I went into the hospital for my surgery (which blew my second semester of school clean out of the water). YES, it's a 'Miracle'!...He can see quite well! :)
Upon, returning home from the hospital I found my husband's health going down hill...FAST!!! I made the decision to quit school so I could find a job. (I had this deep 'feeling' that Larry wouldn't last much longer and I [like Misty] would find myself fending for myself and my kitties.)
Through a 'recently' formed local area cat rescue organization, I reluctantly managed to find homes for Misty, Pepper and our 'special' Squeaks. This allowed me more time to take care of Larry and the baby kittie while looking for work.
I was left with only had Leo who was self sufficient, other than having to clean his 'box', and baby Corpsy (pronounced Corey. I found his litter on Army Corps of Engineers land while I had a friend with me who is an ACE Officer. I was showing my Officer friend the remains of some deer that had been poached). Corpsy was still too young to allow out of his 'nursery box'. So I had my hands full looking for a employment, taking care of a sick and dying husband and raising my 'replacement' for Leo (whom I thought would go LOOOONG BEFORE Larry). I wound up burying Larry the day before Halloween 2004 instead of Leo as I thought would happen.
So poor Leo 'NOW' has yet another YOUNGSTER to put up with!!! Even though his hyperthyroidism was starting to affect him more and more he somehow knew what was going on and helped me train Corpsy. Once he was sure Corpsy could go it without him (May of 2005) he gave up just as Larry did before him. I had to take him to the local Humane Society and have him euthanized. I couldn't even bring him 'home' to bury him as I had done with so many pets before him since I had no place to put him. Larry went into a plot his parents left behind when they went to Ohio and died and were buried there. Larry was 61. Leo was 18.
At 48 and with some slight disabilities which force me to try to break into a new vocation, I am STILL looking for 'job $ecurity' of some sort. A good friend has taken ME in (WITH Corpsy...of COURSE!) Corpsy will be three in July. HE is the one who keeps ME going now. (I have no children of my own. Larry's kids are grown, have kids of their own and could care less if I live or die.)
So you see 'youngsters' CAN keep you going even though they take more energy. They FORCE you to keep the energy up...which is a GOOD thing!!!!! :)