Hand pumping is completely feasible if you are in decent health - you don't need to be an athlete, but it does take some effort to do. But more effort is what most people seem to need in life these days - we live with too much comfort . . . and it is way easier than running a mile!
The key to hand pumping is that each session should be limited to about 50 strokes of the pump, once the line is charged. Then you stop, vent the line, and let the pump cool down before resuming. This keeps the pump cool, and that is what keeps water from making it into your gun. If you pump much more that that the pump will heat up, and then hot air makes its way into your gun - and that hot air will carry a lot of water vapor that will later condense into liquid when it cools down.
If you approach your shooting in a manner that you stop and refill the gun at about that 50 stroke limit, everything works well. You don't waste time waiting for the pump to cool down, and 50 strokes is not that hard to do. I used to tune my guns to shoot two or three magazines off one 50 stroke filling session, and it was very manageable. That said, that was with moderate power .22 and .25 cal guns - with high power big bores that would be different; one shot could be a whole pumping session, depending on the FPE. But I could easily shoot 600+ FPE worth of shots on one 50 stroke pumping session that would take about three minutes to complete.
If you insist on shooting every last shot the gun is capable of before refilling, then you are probably in for a long pumping session. This can be fine if you are basically done for the day, and want to refill it while doing something else - like pump it during commercials while watching TV, cooling down the pump while the show is on - but is very limiting while actively shooting.
Filling a gun from empty is the part that is no fun - that will take quite a while. You can probably pump continuously for the first 150 strokes or so from empty, as the pressure is low and the pump won't heat up much, but after that you will need to be on the 50 stroke plan. Depending on the gun, the initial fill might be 400 or more strokes of the pump.
I started with a hand pump and did it for years. What moved me to a tank (and eventually a compressor) was working on the guns themselves - that caused me to have to pump from empty often, and that just was not fun (especially when I tried something that did not work, and had to immediately empty it and then refill again). But pumping to actually shoot was not bad - at least with guns that max out at about 3000 psi or less.
So maybe filling from zero or shooting big bores might be like running a mile, but filling for a short moderate power shooting session is no worse than walking a lap on a track, and faster too . . .