Outdoor activities can be very effectively used as an energiser during conferences and events. It's very important to understand energy and how the typical conference environment can be counterproductive if you want to get the best out of your delegates.
A common scenario is a conference in a hotel. Delegates may have been up late into the previous night socially bonding over a few drinks. The following morning they may feel a little jaded. There will be a hearty breakfast in the hotel and then they will head for the conference room. Some of the delegates may not have been outside to get any fresh air.
The conference room itself may also not be the best surroundings if you want optimum mental performance and creativity from delegates. Air conditioning, artificial lighting and the soporific tones of a speaker who has found their stride can all combine to send delegates into a hypnotic state that isn't the most condusive if two way participation is the aim.
Various studies have found that the maximum time that a person can focus on one subject is +/- 45 minutes (Mihaly Csikszentmihalyi et al) but that concentration starts to lag after 15 minutes. The suggested optimum model has been suggested as 45 minutes focus and 15 minutes break in each hour.
Energiser activities need to be engaging. If you suggest people have a walk first thing in the morning then you may not get a full turnout. You might consider having a team building session after breakfast and then heading back to the conference room. That would certainly blow any 'cobwebs' away and leave an energised and motivated team for the conference session.
A good facilitator will have suitable activities up their sleeve to ensure that delegates are engaged. The format of half a day of activities and half a day of conference does seem to be effective in breaking the day up and increasing focus in the room.
Apart from anything else an event needs to be enjoyable. Fun is very powerful and it's often avoided in business, but most of us know from our own experiences that fun works.