It’s sometimes difficult and the last thing you ever want to do is to put a crochet project down to give your hands (arms, shoulders, head too!) a rest. But, that is the best thing you can do if you plan on crocheting the rest of your days :p)
A note about changing your hook. If you use a metal hook switching to a wooden/bamboo one can help. The wood/bamboo hooks will take in the warmth of your hand and you’ll last a little longer. But, still resting is the best thing you can do to help you with hand-fatigue. Try putting your project down after crocheting about 20-30 minutes, flex out those fingers, roll your shoulders and rest for a bit. Your hand will tell you how it feels as soon as you pick up that hook again. Remember this is an enjoyable hobby for most of us and shouldn’t hurt!