OM,
Perhaps you could become a defender, start taking much more pride in staunchly defending against all these younger forwards, and furnish solid stabilizing support for your forwards.
Defense can be much more consistent than the obvious needs of offensive strike capabilities, speed, pinpoint precision, and lightning reflexes. I've found that learning to really study defense and developing the pro's speed of mental calculation and recognition of the opponent/s' strategies is just as attainable, and perhaps even more so, than that of a forward's need to recognize the D and execute an attack as perfectly as possible.
As one gets older, one should be able give up the youthful urge to just race a shot or kill oneself and burn up too much energy doing a high speed shuffle. Percentage play (from decades of observation) concludes that in any advanced foos over rookie level, there are really only 3-4 lanes where the ball will approach the or go towards the goal. If you collect videos and tapes, check them over the decades and see if any legend or proMaster uses more than those 3-4 lanes. Humans just practice those. Noone really thinks of doing a thousand shots to the first dot, then the first and 1/4 dot, then the first and 1/2 dot, and so on through the other side. If some insane individual does this and perfects an 18lane shooting series, then you have even less hope of blocking or defeating that one than you would a Rico or Spredeman.
Concluding this, then establishing the closest thing to a generically sound D is:
1. Observe if possible the forwards to be defended against. They will most likely have one, two or three, rarely four lanes that they go through. And some defenses, either because it hides these lanes or they just have bad mental memories of shooting on those types of D's, will always bother them while others make them "groove".
2. Develop one or two defenses for different lane threats and once you get this philosophy down, add one or more feints to those same D's, to throw in to distract or at least discomfit the opposing forward.
3. Develop at least two set on-goal shots from the goal, like a square pull set and a spray push set, so you can easily switch to whichever shot set is harder or less familiar to the defenders... at the very least making them work a little more.
4. Add one or two pass or clear solidly practiced option releases away from the goal, and FORCE yourself to employ these every so often, for obvious reasons like keeping the defenders honest and to prevent their getting comfy whenever you have the ball.
None of these require blinding speed, just good careful observation, whenever possible, of your opposing human opponents, to find their shot lanes. And good quick calculation of the percentages as each shot develops. Just like poker. And of course, technique. Many techniques and styles are available, and their speed and reaction time comes from execution, not physical brute force or power. Even if forwards mis-hit shots earlier, and score, they will more likely than not warm up into shooting their normal lanes as the game and match goes along, not continuing the slop or accidental releases. And the madder and less detached they get, the more they will groove into the same lanes.
I would suggest never never again go into any game, pickups for fun, or matches for the money, without some gameplan and the effort to establish it. No matter what. A thinking goalkeeper who practices this should be a lot more dangerous than those who do not. Oh sure, forwards will still score and sometimes drill the goalkeeper, but the trick is to fight to minimize the percentages and to consistently give you and/or your team a chance to win. If a goalkeeper can hold off a dominating forward just enough and consistently enough to either score or have one's forward outscore the opponents, that is definitely a thousand times better than bricking the opposing forward every 7th game or so, but getting rolled and fileted in all the other games.
The other suggestion is to learn to make timeout calls and to start controlling the play, which can be tons of fun. I teach this to young goalkeepers and they get some empowerment immediately. How? If the opponent/s is trying to speed up the game, slow it down, just enough. If they try to slowplay, throw some quicksets, even hacks into the game, lots of things to force the play to speed up. Then forcibly reverse it... decide to shoot or release at 14.5 secs, then 3 secs the next, then 7 secs the next. Play with the timing. Younger or more "feel" players will often get pulled along as if on a string. This also allows one to be a calming influence on one's partner, never shooting when they're not ready or wasting opportunities with brash clears that they don't have a fair chance to catch.
If you love this game, there is a frightening amount of logic, technique, timing, and percentage calculation in it, too. I'm sure that Gumby and Tmac have switched more and more to technique, timing, percentage and overall philosophy to win matches as they've gotten older and farther removed from their first wins 2 decades ago.. What I believe you have to give up is the youthful, invincibility-deluded desire to play like you did when you were just beginning to get good. Smoothness over speed, timing over power, and teamwork over heroic feats. Try to perfect your self-control within your own current limitations. Then extend that control beyond just yourself, with practice and philosophy, to make them play your game. Just like all head-to-head sports, solid tough D is practice-able and can be made consistent, without the need for superstars and super talent, and a lot of offense can be generated from that D.