If you're snowboarding, towards the end of the day when your legs start to give out, it can become a nightmare. If you're traveling and you hit a bunch of logistical snags that throw off your timetable, it can be intensely stressful if you're trying to coordinate for a group. If you're putting together new sales presentations, it can be nerve-wracking trying to put together all the creative materials and prep you need to do a good job, meanwhile facing the uncertainty.
Take a look what all these have in common.
Look at the tougher parts of those experiences: sore legs and fatigue while snowboarding, disorientation and annoyance at details getting thrown off while traveling, uncertainty and deadline-crunch when prepping for a brand new sales presentation.
What do they have in common?
They fade greatly over time.
Fatigue is one thing that's tremendously unenjoyable when you're feeling it, but doesn't get strongly encoded in your memory. Neither does stress from coordinating nor deadline pressure.
These are actually the kinds of things that people enjoy tremendously when looking backwards. Snowboarding, especially the last runs of the day, are remembered fondly (even if you felt like you were dyin' when it was happening). Getting lost and thrown off while traveling can lead to immensely cool experiences in retrospect. Coming up against deadline pressure becomes a fond memory when looking back later.
That means something interesting is available to you -- you can realize that you're going to enjoy the moment tremendously later looking back, and then simply decide to start enjoying it now.
Those moment-by-moment unpleasant emotion and stress doesn't really encode in your memories. When you reflect on how you'll feel later, you might realize that an experience that's awful in the moment will feel great later.
So why not enjoy it right now? It's entirely up to you. Even when your body and biochemistry are worn down, the highest thinking part of you can take great pleasure in what's happening -- perhaps even moreso than normal, enjoying the fact that this is going to make a tremendous memory later.